BCDC 12 (1829) DTZS  
©TBS 2023 -All rights reserved  First Edition  2023  
DRAFT TANZANIA STANDARD  
Guidelines for Construction of Wooden Boats for the Indian Ocean and 
Inland Waters  
TANZANIA  BUREAU  OF STANDARDS  
BCDC 12 (1829) DTZS  
i  ©TBS 2023 -All rights reserved  This draft Tanzania Standard was published under the authority of the Board of Directors of Tanzania 
Bureau of Standards on 2023 -mm-dd.  
Tanzania Bureau of Standards (TBS) is the statutory national standards body for Tanzania established 
under the Standard s Act No. 3 of 1975, repealed and replaced by the Standards Act No. 2 of 2009.  
The Building and Construction Divisional Standards Committee (BCDC), under whose supervision this 
Tanzania Standard was prepared, consists of representatives from the following  organizations:  
*College of Engineering and Technology, University of Dar er Salaam  
Ministry of Works and Transport (MoWT)  
*National Housing Corporation (NHC)  
Contractors Registration Board (CRB)  
Ardhi University (ARU)  
Jeshi la Kujenga Taifa (JKT)  
*Natio nal Estates and Designing Consultancy Company Ltd (NEDCO)  
Architects and Quantity Surveyors Registration Board (AQRB)  
Institution of Engineers Tanzania (IET)  
*National Construction Council (NCC)  
Engineers Registration Board (ERB)  
The organizations marked with an asterisk (*) in the above list, together with the following were directly 
represented on the Technical Committee entrusted with the preparation of this draft Tanzania 
Standard:  
Tanzania Forestry Research Institute (TAFORI)  
Sokoine University of Agriculture (SUA)  
Sao Hill Industries Ltd  
Tanzania International Bee Co. Ltd  
Tanzania Shipping Agencies Corporation (TASAC)  
Tanzania Bureau of Standards  
P O Box 9524  
Dar es Salaam  
Tel: +255 (22) 2450206/2450949/2450298  
Fax: +255 22 2450298  
E-mail: info@tbs.go.tz   
Website: www.tbs.go.tz  
  
©TBS  2021 -All rights reserved  ii Contents  
Abbreviations  ................................ ................................ ................................ ................................ ................................ . v 
0 National Foreword  ................................ ................................ ................................ ................................ .......................  1 
1 Scope  ................................ ................................ ................................ ................................ ................................ ..........  2 
2 References  ................................ ................................ ................................ ................................ ................................ .. 2 
3 Terms  and definitions  ................................ ................................ ................................ ................................ ..................  3 
4 Materials and Fasteners  ................................ ................................ ................................ ................................ ..............  4 
5 Determination of Scantlings  ................................ ................................ ................................ ................................ ...... 12 
6 Manufacturing Facilities and Workmanship  ................................ ................................ ................................ ...............  59 
7 Compliance and Boats Identification  ................................ ................................ ................................ .........................  60 
Annex A  ................................ ................................ ................................ ................................ ................................ ....... 63 
Annex B  ................................ ................................ ................................ ................................ ................................ ....... 67 
Annex C  ................................ ................................ ................................ ................................ ................................ ....... 69 
Annex D  ................................ ................................ ................................ ................................ ................................ ....... 73 
 
List of figures  
Figure 1: Boats leading dimensions  ................................ ................................ ................................ ...............................  4 
Figure 2 : Component parts of a wooden hull  ................................ ................................ ................................ .................  6 
Figure 3: Cross section of a round bilge wooden hull ................................ ................................ ................................ ..... 7 
Figure 4 : Typical section Chine Hull  ................................ ................................ ................................ ...............................  8 
Figure 5: Sawing of Timber  ................................ ................................ ................................ ................................ ..........  11 
Figure 6: Common types of bolted scarphed joints  ................................ ................................ ................................ ...... 13 
Figure 7: Typical hooked keel scarph showing position of stopwaters  ................................ ................................ .........  16 
Figure 8: Typ ical connection of ballast keel to falsekeel  ................................ ................................ ..............................  16 
Figure 9: Typical scarph connection stem to woodkeel  ................................ ................................ ................................  17 
Figure 10: Typical connection of sternpost to keel and counter timber  ................................ ................................ ........  18 
Figure 11: Typical floors  ................................ ................................ ................................ ................................ ...............  24 
Figure 12: Spacing of butts  ................................ ................................ ................................ ................................ ..........  32 
Figure 13: Typical butt straps on s ingle skin hull planking  ................................ ................................ ...........................  33 
Figure 14: Connection of single skin planking to centreline structure (for normal breadth of planking)  ........................  34 
Figure 15: Strip planking  ................................ ................................ ................................ ................................ ..............  35 
Figure 16: Arrangement of fastening in double skin hull planking  ................................ ................................ ................  38 
Figure 17: Detail of gunwale for double skin planking  ................................ ................................ ................................ .. 38 
Figure 18: Dowel fastening of beam at shelf  ................................ ................................ ................................ ................  40 
Figure 19: Butts of deck planking  ................................ ................................ ................................ ................................ . 45 
Figure 20: Deck fastening (laid decks)  ................................ ................................ ................................ .........................  46 
Figure 21: Conformity Label Example  ................................ ................................ ................................ ..........................  61 
Figure 22: Example of Twelve -Digit Hull Identification Number (HIN)  ................................ ................................ ..........  62 BCDC 12 (1829) DTZS  
iii  ©TBS 2023 -All rights reserved  List of tables  
Table 1 *** Guidance on the selection of timbers for constructional members  ................................ ................................  9 
Table 2: Standard timber density  ................................ ................................ ................................ ................................ . 12 
Table 3: Keel, hog, stem, stern post and fastenings for motor, sailing and auxiliary craft  ................................ ............  15 
Table 4: Frames for Motor. Sailing and Auxiliary Craft  ................................ ................................ ................................ . 21 
Table 5: Floors for motor, sailing and auxiliary craft  ................................ ................................ ................................ ..... 26 
Table 6: Floor fastenings for motor, sailing and auxiliary craft  ................................ ................................ .....................  27 
Table 7: Beam shelf and bilge stringer scantlings and fastenings for motor, sailing and auxiliary craft  .......................  28 
Table 8: Timber bulkheads  ................................ ................................ ................................ ................................ ...........  29 
Table 9: Bulkhead plating and stiffeners for motor, sailing and auxiliary craft  ................................ ..............................  30 
Table 10: Outside and deck planking for motor,sailing and auxiliary craft  ................................ ................................ .... 31 
Table 11: Fastenings for outside end deck planking in motor, sailing end auxiliary craft  ................................ .............  36 
Table 12: Plywood planking: overlaps and fastenings for motor, sailing and auxiliary craft  ................................ .........  39 
Table 13: Plywood planking: butts and butt straps for motor, sailing and auxiliary craft ................................ ...............  39 
Table 14: Beams and hanging knees for motor, sailing and auxiliary craft  ................................ ................................ .. 42 
Table 15:Longitudinal steel items for motor, sailing and auxiliary craft  ................................ ................................ ........  43 
Table 16 : Steel angle beams at upper and cabin decks for motor, sailing and auxiliary craft  ................................ ...... 43 
Table 17: Permissible load on timber pillars  ................................ ................................ ................................ .................  47 
Table 18: Coachroof coaming and deck thicknesses for motor, sailing and auxiliary craft  ................................ ...........  48 
Table 19: Coachroof and deckhouse beams for motor, sailing and auxiliary craft  ................................ .......................  48 
Table 20: Hard Chine vessels – Keel and Hog  ................................ ................................ ................................ ............  49 
Table 21: Hard Chine Vessels Transom  ................................ ................................ ................................ ......................  50 
Table 22: Transom  ................................ ................................ ................................ ................................ .......................  51 
Table 23: Transverse web frames  ................................ ................................ ................................ ................................  52 
Table 24 : Hard Chine Vessels Floo r ................................ ................................ ................................ ............................  53 
Table 25: Hard Chine vessels bottom stringers  ................................ ................................ ................................ ...........  54 
Table 26: Hard Chine vessels Chines  ................................ ................................ ................................ ..........................  55 
Table 27: Chines and Stringers (Single planked hulls)  ................................ ................................ ................................ . 56 
Table 28: Hard Chine Vessels - Beam Shelf/ Sheer Clamp  ................................ ................................ .........................  56 
Table 29: Hard Chine Vessels - Hull Planking Thickness  ................................ ................................ ............................  57 
 
Table   C.1: Keel, hog, stem, stern post and fastenings for motor, sailing and auxiliary craft  ................................ ...... 69 
Table   C.2: Frames for Motor, Sailing and Auxiliary Craft  ................................ ................................ ...........................  69 
Table   C.3: Floors for motor, sailing and auxiliary craft  ................................ ................................ ...............................  69 
Table   C.4: Floor fastenings for motor, sailing and auxiliary craft  ................................ ................................ ................  69 
Table   C.5: Beam shelf and bilge stringer scantlings and fastenings for motor, sailing and auxiliary craft  ..................  70 
Table   C.6: Timber bulkheads  ................................ ................................ ................................ ................................ ..... 70 
Table   C.7: Bulkhead plating and stiffeners for motor, sailing and auxiliary craft  ................................ ........................  70 
Table   C.8: Outside and deck planking for motor. Sailing and auxiliary craft  ................................ ..............................  71  
©TBS  2021 -All rights reserved  iv Table   C.9: Fastenings for outside end deck planking in motor, sailing end auxiliary craft  ................................ ..........  71 
Table   C.10: Beams and hanging knees for motor, sailing and auxiliary craft  ................................ .............................  71 
Table   C.11: Longitudinal steel items for motor. sailing and auxiliary craft  ................................ ................................ .. 71 
Table   C.12: Steel angle beams at upper and cabin decks for motor, sailing and auxiliary craft  ................................ . 72 
Table   D.1: Hard Chine vessels – Keel and Hog  ................................ ................................ ................................ .........  73 
Table   D.2: Hard Chine Vessels Transom  ................................ ................................ ................................ ...................  73 
Table   D.3: Transom  ................................ ................................ ................................ ................................ ...................  73 
Table   D.4: Transverse web frames  ................................ ................................ ................................ ............................  73 
Table   D.5: Hard Chine Vessels Floor  ................................ ................................ ................................ .........................  73 
Table   D.6: Hard Chine ves sels bottom stringers  ................................ ................................ ................................ ........  73 
Table   D.7: Hard Chine vessels Chines  ................................ ................................ ................................ ......................  73 
Table   D.8: Chines and Stringers (Single planked hulls)  ................................ ................................ .............................  73 
Table   D.9: Hard Chine Vessels - Beam Shelf/ Sheer Clamp  ................................ ................................ .....................  74 
Table   D.10: Hard Chine Vessels - Hull Planking Thickness  ................................ ................................ .......................  74 
 BCDC 12 (1829) DTZS  
v  ©TBS 2023 -All rights reserved   Abbreviations  
BS British Standard  
HIN Hull Identification Code  
HP  Horsepower  
ISO International Organization  for Standardization  
KW Kilowatt  
LOA Length Overall  
LWL Length Waterline  
MIC Manufacturers Identification Code  
MOE  Modulu s of Elasticity  
MOR  Modulus of Rupture  
TASAC  Tanzania Shipping Agencies Corporation  
UK United Kingdom  
WBP  Water and Boil Proof  
AS/NZS Australian /New  Zealand StandardDRAFT TANZANIA STANDARD  BCDC 12 (1829) DTZS  
1  ©TBS 2023 -All rights reserved   0 National Foreword  
The Tanzania  Bureau  of Standards  is the statutory  national  standards  body  for Tanzania,  established  
under  standards  Act No. 3 of 1975,  amended  by Act  No. 2 of 2009.  
This draft Tanzania  Standard  is being  prepared  by BCDC  12 Timber structures  technical  committee  
under  the supervision  of the Building  and Construction  Divisional  Committee  (BCDC).  
Attention is drawn to the possibility that some of the elements of this document may be the subject of 
patent rights. Tanzania Bureau of Standards (TBS) shall not be held responsible for identifying any or 
all such patent rights. 
©TBS 2023 -All rights reserved  2 Guidelines for Construction of Wooden Boats for the Indian Ocean and 
Inland Waters  
1 Scope  
1.1 These Guidelines, apply to the construction of any new wooden vessel of be tween 6m etres  length 
over all (L OA) to less than 24m etres  length, constructed under the inspection of  the overseeing 
authority . The Guidelines  specifies minimum standard for the design, construction, inspection and 
certification of the hull, and outfit of wooden vessels for the Indian Ocean and Inland Waters.  
1.2 “Surveyor” refers to an officially appointed Surveyor by the  overseeing authority   
1.3 For certification of build to this Standard, vessels are to be completed in accordance with the 
specification s and drawings  approved by the overseeing authority .  Any variations to the scantlings, 
materials, equipment and layout as set out in the approved specification, drawings, and these 
Guidelines , are to be submitted to  the overseeing authority  for approval, p rior to the proposed 
variation being put in hand.  
1.4 Workmanship is to be in accordance with boatyard operating procedures  approved by the overseeing 
authority  and to the approval of the Surveyor.  
1.5 All vessels are to comply fully with current statutory require ments.  
1.6 Wooden vessels of unusual form and dimensions or of a design not covered by these Guidelines , 
may receive individual consideration for approval upon submission of full details to the overseeing 
authority . 
1.7 Compliance with these Guidelines does not re lieve the designer or boatbuilder of a vessel of their 
responsibilities to the owner for the specification requirements or performance of the completed 
vessel.  
1.8 The boatbuilder is to provide the Surveyor(s) with full access to the facilities during normal w orking 
hours to carry out their duties in surveying for compliance with these Guidelines . 
1.9 These Construction Guidelines may be used as guidance for the repair of the wooden vessels.  
1.10 Vessel types are not covered by the requirements of these construction Gui delines including the 
following:  
• Vessels of simple construction including vessels such as rafts and dug -out canoes;  
• Vessels judged by the overseeing authority to be outside the scope of this guideline.  
2 References  
The following documents were referred o n preparation of these Guidelines:  
BS 1088:2018 - Marine plywood. Requirements   
AS/NZS 2272:2006 - Plywood —Marine  
TZS 656:2021 - Copper/chromium/arsenic composition for the preservation of timber — Specification  
BS EN 301:2017 - Adhesives, phenolic and aminoplastic, for load -bearing timber structures. 
Classification and performance requirements  
BS 3452:1962 - Specification for Copper/Chrome water -borne wood preservatives and their application  
ISO 2081:2018 -Metallic  and other inorganic coatings — Electroplated coatings of zinc with 
supplementary treatments on iron or steel  
ISO 12215 -1—Small craft - Hull construction and scantlings - Part 1: Materials: Thermosetting  resins, 
glass -fibre reinforcement, reference laminat e 
ISO 12215 -3—Small craft - Hull construction and scantlings - Part 3: Materials: Steel, Aluminium  alloys, 
Wood, other materials  
ISO 12215 -4—Small craft - Hull construction and scantlings - Part 4: Workshop and manufacturing  
ISO 12215 -5—Small craft - Hull construction and scantlings - Part 5: Design pressures, design stresses, BCDC 12 (1829) DTZS  
3 ©TBS 2023 -All rights reserved  scantling determination  
ISO 12215 -6 - Small craft - Hull construction and scantlings - Part 6: Structural arrangements and details  
Other references  
Merchant Shipping Cap.165  
Merchant Shipping (Small Ships, Local Cargo Ship Safety, Small Ship Safety, Surveys and Inspections 
for Vessels Engaged on Local and Coastal Voyages, Inland Waters) Regulations, 2006  
Rules and regulations for the classification of Yatchs and Small Craft, Part 2 Hul l Construction, Lloyd's 
Register of Shipping  
Uniform Shipping Laws Code 2008, Section  5M: Construction -Timber ( CTH, NSW, NT, QLD, SA, TAS, 
VIC & WA)   
The Commercial Timbers of Tanzania by J.M. Bryce and Revised by A.W.  Chihongo. Third edition 2003, 
published by Tanzania Forestry Research Institute  
Sea Fish Authority (UK ), Construction  Standards for Wooden fishing vessels  
3 Terms  and definitions  
For the purpose of this Standard the following terms and definitions apply.  
3.1 Length  
3.1.1  The overall length, LOA, is the distance, in metres, measured parallel to the static load waterline 
from the fore side of the stern to the after side of the stern or transom, excluding rubbing strakes 
and other projections.  
3.1.2  The waterline length, LWL, is the distance, in metres, mea sured on the static load waterline from 
the fore side of the stem to the after side of the stern or transom.  
3.1.3  The scantling length, L, is to be taken as:  
𝑳=𝑳𝑶𝑨+𝑳𝑾𝑳
𝟐 𝒎𝒆𝒕𝒓𝒆𝒔   (See Figure 1)  
3.1.4  Amidships is to be taken as the middle of the static load waterline.  
3.2 Breadth/ Beam  
3.2.1  The breadth/beam, B, is the extreme breadth, in metres, measured between the outer sides of the 
hull, excluding rubbing strakes or other projections.  
3.3 Depth  
3.3.1  The depth, D, is the distance, in metres, at amidships, measure d from the bottom of the keel, or 
ballast keel if fitted, to the top of the main deck or gunwale at side.  
3.3.2  It is assumed that a sailing or auxiliary craft is fitted with a ballast keel. If a centreboard is fitted the 
depth, D, is, in general, to be the meas ured depth increased by 15 percent, but will be considered 
for each individual design.  
3.4 Scantling dimensions  
3.4.1   The dimensions of the structural parts; often described in terms of moulding (depth) and siding 
(width).  
The moulded dimension  of any piece is its dimension measured in from the outside toward the 
interior of the hull.  
The siding is the direction at right angles to the moulded dimension that is not running along the 
length of the wood grain.   
©TBS 2023 -All rights reserved  4  
Figure 1: Boats leading dimensions  
3.5 Speed  
3.5.1  The speed, V, is the maximum speed, in knots.  
In general, the guideline applies to vessels operating at moderate speeds (maximum operating speed 
20 knots). Vessels operating at higher speeds will require special consideration by the overse eing 
authority.  
4 Materials and Fasteners  
4.1 General Characteristics  
4.1.1  All materials used in the construction of a new vessel are to be in accordance with the approved 
building specification.  
4.1.2  When selecting materials and equipment to be used in the vessel construction, designers and 
boatbuilders of new vessels will need to pay special regard to the working conditions to which the 
vessel will be subjected, and should take all measures to ensure that any material or appliance 
fitted in accordance with the requirements of these Guidelines is suitable for the purpose intended, 
having regard to its location in the vessel, the area of operation, and the weather conditions which 
may be encountered by t he vessel.  
BCDC 12 (1829) DTZS  
5 ©TBS 2023 -All rights reserved  4.1.3  Boatbuilders are advised that any requirement for goods or materials to comply with specified 
Guidelines  shall be satisfied by compliance with a specification sufficiently detailed to permit 
assessment for goods or materials of an innovative nat ure (or subject to innovative processes of 
a manufacture such that they cannot comply with a specification) and which fulfil the purpose 
provided by the specified Guidelines ; provided that the proposed Guidelines , code of practice, 
specification or technic al description provides, in use, equivalent levels of safety, suitability and 
fitness for purpose.  
4.2 Timber species  
4.2.1  The species of timber which may be used for the various constructional members see Fig ure 2, 3 
and 4 are given in Table  1 and Annex A . It is presumed that the designer will relate the known 
characteristics, e.g., swelling and shrinkage, strength, density, bending and working capabilities, 
of particular species to the constructional design.  
4.2.2   A general indication of their known performance  in service has been experienced, but in view of 
the differences in construction methods and in the use of the craft, design considerations may 
influence the selection of species.  
4.2.3  The inclusion of a timber in Table 1 does not imply that all material availa ble under the particular 
name is suitable for the use shown, and care must be exercised to ensure that an appropriate 
grade is obtained.   
©TBS 2023 -All rights reserved   6  
Figure 2: Component parts of a wooden hull  
1. Ballast keel  
2. Wood keel  
3. False keel  
4. Stem  
5. Sternpost  
6. Deadwood  
7. Rudder  
8. Rudder heel fitting  9. Frames or Timbers  
10. Floors  
11. Beam shelf  
12. Clamp  
13. Carling  
14. Bilge Stringer  
15. Mast set  
16. Outside planking  17. Bulwark  
18. Transom  
19. Beams  
20. Half beams  
21. Carling  
22. Tie rods  
23. Lodging knees  
24. Hanging knees  25. Coach roof coaming  
26. Deck  
27. Margin plank  
28. Covering Board  
29. King plank  
30. Mast partner chock  
31. Coach roof beams  
32. Coach roof top  33. Keel bolts  
34. Tiller  
35. Mast  
 
 
 
 
 
7 ©TBS 2023 -All rights reserved   
 
Figure 3: Cross section of a round bilge wooden hull  
 
 
©TBS 2023 -All rights reserved   8 
 
Figure 4: Typical section Chine Hull   
Key: 
1. Keel 
2. Hog 
3. Hitch floor  
4. Web frame  
5. Bottom stringer  
6. Bottom planking  
7. Gusset or chock  
8. Chine  
9. Topside stringer  
10. Topside frame  
11. Topside planking  
12. Beam shelf  
13. Hanging knee  
14. Deck beam  
15. Deck plank  
16. Sheer clamp  
  
9 ©TBS 2023 -All rights reserved  Table 1*** Guidance on the selection of timbers for constructional members  (Other type of timber species 
may be used for different construction members and should meet the requirements for density stated under 
Table 2)  
SN. Construction Members  Timber  
1 Keel, false keel, Deadwood, Ballast keel and Hog  Adina  
Mkongo ( East African Afzelia ) 
Muhuhu  
Nkunya  
Loliondo  
Mkwaju  
Mninga  
Mwangaa (East African 
Afrormosia)  
2 Stem  Muninga  
Mvule  
Mkongo ( East African Afzelia ) 
Teak  
3 Sternpost  Mkongo ( East African Afzelia ) 
Mninga  
Mninga  maji  
Muhuhu  
Nkunya  
4 Bilge and chine stringer  
Beam shelf, stringer, Bulkheads and clamp  Mkongo ( East African Afzelia ) 
East African Mahogan  
Mtondoo  
Mtandarusi  
Mfimbo  
Nkunya  
Mninga  
Teak  
5 Floors, Engine beds  East African Afrormosia 
(Mwangaa)  
Muhuhu  
Nkunya  
Knobthom  
Mkwaju  
Mninga  
Teak  
6 Frames  Mkongo ( East African Afzelia ) 
Mtanga  
Mvule  
Nkunya  
Mninga  
Mkoko (Rhizophora mucronata)  
7 Hull planking  Mkongo ( East African Afzelia ) 
Muhuhu  
Nkunya  
Mninga/ m ninga maji  
Mvule  
Mtondoo  
Teak  
8 Deck planking  Mkongo ( East African Afzelia ) 
East African mahogany  
East African Comphorwood  
Muhuhu   
©TBS 2023 -All rights reserved  10 SN. Construction Members  Timber  
Mkwaju  
Mvule  
Teak  
9 Beams and carlings  Mkongo ( East African Afzelia ) 
Muhuhu  
Nkunya  
Loliondo  
Mkwaju  
Mninga  
10 Knees  Mkongo ( East African Afzelia ) 
Muhuhu  
Nkunya  
Loliondo  
Mkwaju  
Mninga  
Mkoko (Rhizophora mucronata)  
*** The species of timber which may be used for the various constructional members , see Fig ure 2, 3 
and 4 are given in Tables and Annex A . For woods with local names, one can refer to Annex A  to identify 
the presented name.  
4.3 Timber quality  
4.3.1  The timber is to be of good quality and properly seasoned and is to be free from heart  rot, sapwood, 
decay, insect attack, splits, checks,  shakes and other  imperfections which would adversely affect 
the efficiency of the material. It is also to be generally free from knots, although an occasional 
sound intergrown knot would be acceptable.  
4.3.2  The timber for the centreline members is to be reasonably seasoned and , where there is a risk of 
excessive drying -out, it is to be coated with boiled linseed oil or varnish, as soon as erected, to 
prevent splitting.  
4.3.3  The material for hull and deck planking is to be generally plain grained and, for deck planking, is 
to be quar ter sawn ( see Figure 5). 
 
 
 
11 ©TBS 2023 -All rights reserved   
Figure 5: Sawing of Timber  
4.4 Timber moisture content  
4.4.1  The timber is to be stored under dry conditions and is to have an air -dried moisture content of not 
more than about 20 % before use. Care is to be taken to avoid excessive drying -out during building.  
4.4.2  The moisture content of material which is to be glued is  to be about 15 %. Contents slightly above 
this value are recommended when resorcinol glues are used, and contents slightly below this value 
are recommended when phenolic or urea -formaldehyde resins are used. It is recommended that 
the material to be used in laminating members should be kiln -dried to about 15 %. 
4.4.3  The moisture content of hull and deck planking which is to be sheathed using synthetic resins is 
to be as low as practicable, to avoid affecting the efficiency of the sheathing bond.  
4.5 Plywood  
4.5.1  The ply wood used in the hull and deck structure is to be of an approved high -grade marine quality 
with good quality face and core veneers of a durable hardwood species and made with high 
standards of workmanship in the lay -up and manufacture. The veneers are to b e bonded with a 
WBP (water and boil proof) type adhesive, although in special circumstances an adhesive of 
slightly lesser durability will be considered. Material complying with BS 1088, or other equivalent 
specification, is acceptable.  
4.5.2  Plywood sheets are to be stored flat on a level bed and under dry, well -ventilated conditions. The 
moisture content is not to exceed 15 %. 
4.6 Timber preservatives  
4.6.1  Preservatives are to be of suitable types, either from the waterborne fixed salt group such as 
copper chr ome type to BS 3452 and copper -chrome -arsenic types to  TZS 656 , or from the organic 
solvent group, such as naphthenates of zinc and copper and pentachlorophenol. Other types of 
preservatives will be considered.  
4.6.2  In the selection of type of preservative, due  regard should be paid to the effect on varnish and 
paint coatings, and on synthetic resins, where sheathing is to be applied.  
4.7 Timber adhesives  
4.7.1  The glues to be used in the construction and lamination of structural members are to be of a gap -
filling resorci nol or phenolic type, such as those complying with  BS EN 301 , or other adhesives 
which have similar durability and can give a WBP bond.  
4.7.2  The glues are to be mixed and applied in accordance with the manufacturer's instructions with 
regard to the shop tempera ture and humidity requirements. Attention is also to be paid to the 
application techniques for the species of timber being glued, and the manufacturer's advice should 
be sought in the working of difficult timbers and the effect of preservatives on the adhe sive. 
4.8 Metal fastenings  
4.8.1  The materials used for fastenings are to be a suitable composition of the following metals: - 
Copper  
 
©TBS 2023 -All rights reserved  12 Gunmetal  
Galvanized iron  
Galvanized steel  
Silicon bronze  
Aluminium bronze  
Stainless steel  
Monel  
4.8.2  Steel and iron fastenings are to be hot -dipped galvanized, but black iron keel bolts may be coated 
with a suitable composition. Small screw fastenings below about  20 mm in length which cannot be 
satisfactorily hot -dipped may be electroplated zinc, provided that the coating is of a reasonable 
thickness and to an approved specification, such as  ISO 2081 Grade Zn 10.  
4.8.3  Stainless steel fastenings are to be of a suitable grade of austenitic steel.  
4.8.4  Gunmetal fastenings may be used, but where increased strength and corrosion resistance is 
desired, it is recommended that silicon bronze be used. Aluminium bronze may be used, in the 
larger bolt sizes, where increased strength is desired. Brass fastenings are not to be used for 
structural purposes.  
4.9 Other materials  
4.9.1  Other materials intended for stru ctural use are to be of good quality, suitable for the purpose 
intended. Details of these materials are to be stated on the relevant construction drawings.  
4.9.2  Suitable arrangements are to be made to insulate aluminium alloys from timber and dissimilar 
metals.  Paints containing either lead, mercury or copper are not to be used in conjunction with 
these alloys.  
5 Determination of Scantlings  
5.1 Application and General  
5.1.1  The scantlings of motor, sailing and auxiliary craft of conventional form and proportions, up to the 
length of 24 meters  are to be determined from respective scantling tables.  
5.1.2  The scantlings will be specially considered where the craft is of unusual design, form or proportions 
or where either the speed exceeds 20 knots or the length exceed 24m etres . 
5.1.3  Timbe r density  
The scantlings for the timber members shown in Tables are based on the following standard densities, 
which are for an air -dried condition of about 15 % moisture content: - 
Table 2: Standard timber density  
SN. Construction member  Minimum Density(kg/m3) 
1 Frames  720  
2 Floors  
3 Keel 
640  4 Stem  
5 Sternpost  
6 Deadwood  
7 Counter timbers  
8 Hull planking  
560  9 Shelves and clamps  
10 Stringers  
11 Beams and knees  
12 Coach roof coamings  
13 Deck planking  430  
5.1.4  Where the density of the proposed timber differs from the standard density shown in 5.1.3, the 
tabular siding, s, thickness or modulus,  sm2, is to be increased or decreased by direct proportion 
in relation to the ratio of the densities, i.e.   
13 ©TBS 2023 -All rights reserved  Required siding, thickness or modulus = Tabular siding, thickness or modulus ×𝑆
𝑊 
Where :  
S = the standard density of the timber, in kg/m3 
W = the density of the proposed timber, in kg/m3 
m = the tabular moulding.  
The tabular siding or thi ckness is, however, not to be decreased by more than 6 %, except where 
specifically allowed.  
5.1.5  The scantlings of laminate members are to be based on the density of the natural timber and are 
not to be corrected for the final density in the laminated conditio n. 
5.1.6  Laminated timber scantlings  
Where the centerline  assembly, bilge stringers, beam shelves, chine’s or beams are of glued laminated 
construction, the scantlings are to be the same as those determined for solid timber, with the exception 
of frames and beam s as indicated in 5.2.5.3.1 and 5.2.10.1.3, respectively.  
5.2 Scantlings for Round Bilge Vessels  
5.2.1  Wood keel  
5.2.1.1  The scantlings of wood keels or, for motor craft, the wood keel and hog are given in Table 3. 
The Rule moulding is to be maintained throughout but the siding may be tapered towards the 
ends where it is to be not less than the Rule siding of the stem or sternpost. The scantlings of 
craft having deep fin keels will be specially considered.  
5.2.1.2  The rabbet for the garboard strake is to have a faying surface not less than twice the thickness 
of the garboard strake or, for plywood, as given in Table 12  
5.2.1.3  When the length,  L, does not exceed 10 m the wood keel is to be in one length. In larger craft, 
the keel should, where possible, be in one length but when a scarph i s necessary in the 
centerline  structure it is to have a length, L, not less than 6 times the moulding,  m, of the item. 
The scarph is to be of the hooked or tabled type if bolted ( see Fig ure 6), or plain type without 
lips if glued. The depth of the lips is to be about  1
4 to 1
7 of the moulding.  
 
Figure 6: Common types of bolted scarphed joints  
5.2.1.4  Softwood stop waters are to be fitted in bolted scarphs in keels and other centreline structure, in 
way of plank back rabbet and in other posi tions where considered necessary by the Surveyor. 
For typical details, see Fig ures.7 and 8. 
5.2.1.5  Scarphs in the keel and hog are to be at least 1 .5m apart and the keel scarph, where fitted, is to 
be clear of engine seating and, if practicable, of the mast step.  
5.2.1.6  Where the keel is cut for a centreboard the siding is to be increased.  
 
©TBS 2023 -All rights reserved  14 5.2.1.7  Where a mast passes through the deck, the heel is to be supported by a suitable mast step 
extending well forward and aft. The step is to be adequately fastened to the floors and t o the 
wood keel   
15 ©TBS 2023 -All rights reserved  Table 3: Keel, hog, stem, stern post and fastenings for motor, sailing and auxiliary craft  
Length,  
L, m Moulding and siding of keel Siding and 
moulding of stem at 
heel, mm  Siding and moulding of 
stem at head and 
sternpost mm  Diameter of bolts, mm,  
Sailing and auxiliary  Motor  
Moulding.  
mm Siding,  
mm Minimum 
siding of 
keel, mm  
 Sectional 
area of keel 
or keel and 
hog, cm2 Sailing 
and 
auxiliary  Motor  Sailing and 
auxiliary  Motor  Centreline 
structure  Keel scarph  
6 75 150 70 80 90 75 75 75 10 8 
8 90 185 80 130 105 90 90 85 10 8 
10 110 220 90 190 120 110 100 95 12 8 
12 125 255 105 250 140 125 115 105 14 10 
14 140 285 115 310 155 140 125 115 14 12 
16 160 320 125 380 170 160 140 125 16 12 
18 175 355 140 450 190 175 150 140 18 12 
20 195 385 150 520 205 195 165 150 20 14 
22 210 410 165 600 220 210 175 160 20 14 
24 230 435 180 690 240 230 190 170 20 14 
NOTES  
1. In motor craft, the moulding of the keel is to be not less than the siding, and the moulding of the hog is to be not less than t wice the thickness of the outside 
planking.  
2. The Table scantlings are based on a timber having a standard density of 640 kg/m 3 and where timber of a different density is to be used the scantlings are to be 
modified in accordance with 5.1.4. 
  
©TBS 2023 -All rights reserved  16 5.2.1.8  Where a wood false keel is fitted abaft the ballast keel a suitable scarph or tenon is to be 
arranged , see Figure 8.  
5.2.1.9  For size of fastenings, see Table 3.  
5.2.1.10  Structural arrangements in way of centreboard casing will be specially considered.  
 
Figure 7: Typical hooked keel scarph showing position of stopwaters  
 
Figure 8: Typi cal connection of ballast keel to falsekeel  
 
5.2.2  Stem  
 
17 ©TBS 2023 -All rights reserved  5.2.2.1  The scantlings of the stem are given in Table 3 and are to be uniformly tapered from head to 
heel. The scantlings at the heel may be required to be increased, depending on the shape of the 
forefoot, to enable an adequate scarph to the keel to be arranged,  see Figure 8. 
5.2.2.2  Where the hull form is such that there is a large radius at the stem head a suitable apron (or 
fashion pieces) is to be provided to give adequate landing for the outside planking.  
5.2.2.3  For size of fastenings, see Table 3 . 
5.2.3  Sternpost  
5.2.3.1  The scantlings of the sternpost are given in Table 3. The sternpost may be tapered to suit the 
form of the craft but the siding at the after edge of the back rabbet is to be not less than that 
required by Table 3 and care is to be taken to ensure there is adequate materi al to take the 
fastenings of the outside planking.  
5.2.3.2  The lower end of the sternpost is to be tenoned or half -lapped to the keel. An inside deadwood 
or knee is to be fitted and adequately through fastened to the sternpost, and false keel, if 
fitted ,see Fig ure 10. 
5.2.3.3  For size of fastenings, see Table 3.  
5.2.4  Counter timber  
5.2.4.1  The area of the counter timber at its forward end is to be not less than the Rule area of the 
sternpost and may gradually be reduced to 75 % of this area at its after end.  
5.2.4.2  The counter timber is to be securely fastened to the sternpost and it is recommended that, where 
practicable, the sternpost should be tenoned or scarphed to the counter timber and through 
fastened.  
5.2.4.3  For size of fastenings, see Table 3  
 
Figure 9: Typical sc arph connection stem to woodkeel  
 
©TBS 2023 -All rights reserved  18  
Figure 10: Typical connection of sternpost to keel and counter timber  
5.2.5  Framing  
5.2.5.1  General  
5.2.5.1.1  The hull is to be provided with an efficient system of side and bottom framing in conjunction with 
stringers, bulkheads or web frames to provide transverse rigidity.  
5.2.5.1.2  The framing may be arranged transversely or longitudinally or may be a combination of both.  
5.2.5.1.3  All frames are to be bevelled or formed to fay closely against the planking.  
5.2.5.1.4  Where the heels of f rames terminate at the centreline construction members they are to be let 
into and fastened to them unless floors are fitted at every frame.  
5.2.5.2  Types of frames  
5.2.5.2.1  The following types of frames may be used, subject to the limitations given in 5.2.5.2.3 and 
5.2.5.2.4: - 
Type 1  Bent frames only  
Type 2  Grown frames only (Sawn frames)  
Type 3  Laminated frames only  
Type 4  Steel frames only  
Type 5  Grown, laminated or st eel frames with 1 bent frame between  
Type 6  Grown, laminated or steel frames with 2 bent frames between  
Type 7  Grown, laminated or steel frames with 3 bent frames between  
5.2.5.2.2  Alternative framing systems to those in 5.2.5.2.1 will be specially considered.  
5.2.5.2.3  The use of Type 1 is to be confined to craft having a depth, D, not exceeding 3 .0 m for sailing and 
auxiliary or 2 .7 m for motor craft, and Types 5, 6 and 7 are to be confined to depths, D, not 
 
19 ©TBS 2023 -All rights reserved  exceeding 3 .6 m and 3 .0 m, respectively.  
5.2.5.2.4  Where the depth, D, exce eds 3 .6 m for sailing and auxiliary craft or 3 .0 m for motor craft the 
framing must be Type 2, 3 or 4.  
5.2.5.3  Scantlings  
5.2.5.3.1  The scantlings and spacing of the various types of frames are given in Table 4.  
5.2.5.3.2  Where the actual frame spacing of timber frames differs from t hat given in Table 4 the strength of 
grown, bent or laminated frames is to be modified in direct proportion, i.e.  
Actual ( sm2) = Table ( sm2) ×𝐴𝑐𝑡𝑢𝑎𝑙  𝑠𝑝𝑎𝑐𝑖𝑛𝑔
𝑇𝑎𝑏𝑙𝑒  𝑠𝑝𝑎𝑐𝑖𝑛𝑔   
where s and m are the siding and moulding, respectively; the Table siding is to be that after 
correction for density. See 5.1.4. 
5.2.5.3.3  In no case is the mean moulding of grown, bent or laminated frames to be less than two -thirds of 
the actual siding except where an increase in the siding is required by 5.2.5.3.6. In all cases the 
siding is to be suitable for the required fastenings.  
5.2.5.3.4  Where the spacing of steel frames differs from that given in Table 4 the section modulus is to be 
modified in direct proportion.  
5.2.5.3.5  The scantlings d etermined from Table 4 are to be maintained for 3
5𝐿 amidships. Forward of and 
abaft this region the following reductions may be made: - 
Bent or laminated frames  Siding reduced by 10 %. 
Grown frames  Moulding at heel and siding at head and heel 
reduced by 20 %. 
Steel frames  Thickness reduced by 10 percent.   
5.2.5.3.6  In sailing and auxiliary craft,  the framing adjacent to the mast is to be increased each side as 
given below or equivalent arrangements provided:  - 
Type 1:  Bent frames only  Three grown or laminated frames of Type 2 or 3 
scantlings (see Table 4.5.1 ) are to be fitted or, 
alternatively, the siding of three bent frames 
increased by 60 %. 
Type 2:  Grown frames only  The siding of three frames increased by 50 % 
Type3:  Laminated frames only  
Type 4:  Steel frames only  Reverse angles or face flats of the size required for 
plate floors are to be fitted on two frames if D does 
not exceed 3.3 m or on three frames when D is 3.3 
m or greater.  
Types 5, 
6 and 7:  Grown, laminated or steel 
frames with bent frames 
between  The si ding of three grown or laminated  
frames increased by 50 % or reverse  
angles or face flats fitted to three steel frames  
5.2.5.3.7  Where internal ballast is fitted the frames may be required to be increased in strength.  
5.2.5.4  Grown frames  
5.2.5.4.1  Grown frames are to be cut to shape from timber having the required curvature of grain.  
5.2.5.4.2  The siding of each grown frame is to be uniform over its length and the moulding is to be a fair 
taper from heel to head.  
5.2.5.4.3  Grown frames may be butted or scarphed. Scarphs are to be glued and have a l ength not less 
than 6 times the siding. Where frames are butted, the butts are to be close fitted and side clamps 
arranged. The clamps are to have a sectional area not less than that of the frame and a length, 
not less than 12 times the frame siding. The c lamp is to be through fastened to the frame by not  
©TBS 2023 -All rights reserved  20 less than three fastenings on each side of the butt and is to fay closely to the planking.  
5.2.5.5  Bent frames  
5.2.5.5.1  The siding and moulding of bent frames are to be uniform over the length of the frame. Each frame 
is to be in one piece from keel to gunwale and, where the form is suitable, may be continuous 
from gunwale to gunwale.   
21 ©TBS 2023 -All rights reserved  Table 4: Frames for Motor. Sailing and Auxiliary Craft  
Depth, D, m  Type 1 Bent wood 
frames only  Type 2 Grown frame only  Type 3 
Laminated 
frames only  Type 4 Steel frames only  Type 5, 6, and 7  
Combination of grown, laminated and steel 
frames with intermediate bent wood frames  Motor  
Sailing  
and 
auxiliary  
Siding, mm  
Moulding.  
mm 
Frame Spacing  
,mm 
Siding, mm  Moulding, 
mm 
Frame Spacing,  
,mm 
Siding, mm  
Moulding  
mm 
Frame Spacing  
mm Frame  
Frame 
Spacing  
mm Intermedia
te bent 
wood 
frame  Spacing of grown. Laminated or 
steel frames mm  At heel  
At head  
Scantling  
mm 
Modulus  
cm3  
Siding, 
mm 
Moulding  
mm 
One bent 
frame 
between 
Type 5  
Two bent 
frame 
between 
Type 6  
Thee bent 
frame 
between 
Type 7  
1.5 1.8 24 19 155 24 31 24 205 25 25 205 30 x30 x3  0.7 205 25 20 365 470 545 
1.8 2.1 34 25 170 34 40 31 230 31 34 230 30 x 30 x 3  0.8 230 31 23 405 505 580 
2.1 2.4 40 30 185 42 50 37 255 37 43 255 35 x35 x4  1.2 255 37 26 440 540 620 
2.4 2.7 48 36 200 52 61 46 280 43 51 280 45 x45 x4 .5 2.0 280 40 29 475 580 655 
2.7 3.0 56 40 215 62 74 55 305 50 61 305 50 x50 x5  3.0 305 43 33 515 620 695 
3.0 3.3 65 45 230 72 87 65 330 57 74 330 60 x60 x5 .5 4.9 330 47 37 565 665 745 
3.3 3.6    81 100 80 355 62 87 355 65 x65 x 8  7.9 355 50 43 620 725 800 
3.6 3.9    90 117 98 380 69 105 380 75 x 65 x 8 .5 11.5 380      
3.9 4.2    100 140 117 405 78 126 405 85 x65 x 8 .5 14.6 405      
NOTES  
1. For Imitation on use of Types 1, 5, 6 and 7, see 5.2.5.2.3  and 5.2.5.2.4  
2. The Table scantlings of timber frames are based on a timber having a standard density of 720 kg/m3, and where timber of a different density is to be used the 
scantlings are to be modified in accordance with 5.1.4. 
3. The frame spacing given in the Table is measured from centre to centre or, for steel frames, from heel to heel of angles.  
4. Where the sp acing differs from that given in the Table, the value of s m2 (or, for steel frames. the section modulus) is to be modified in direct proportion.  
5. Where Types 5, 6 and 7 are adopted, the scantlings of the grown, laminated, or steel frames are to be as required for Types 2, 3 or 4. respectively.  
  
©TBS 2023 -All rights reserved  22 5.2.6  Floors  
5.2.6.1   General  
5.2.6.1.1  Wood floors are to be cut from timber having a suitable grain or may be laminated.  
5.2.6.1.2  Where, at the ends, the frames are continuous across the centreline structure, floors ar e not 
required but, where practicable, the frames are to be attached to the centreline structure by two 
through fastenings . 
5.2.6.1.3  Limber holes are to be provided in the bottom structure as required for efficient drainage of the 
craft.  
5.2.6.2  Type of floors  
5.2.6.2.1  The type of floor to be fitted is dependent on the frame type adopted as follows; - 
Type 1:  Bent frames only (a) Strap floors on every frame within 3/5 L amidships (on 
alternates if D does not exceed 2 .7 m for sailing and auxiliary 
craft or 2.4 m for motor craft) and on every third frame 
forward and aft.  
(b) Angle floors spaced as for strap floors in (a).  
(c) Where 3/5 L amidships falls within the waterline length 
floors are to be on alternates to end of waterline.  
(d) The fitting of wood floors in association with bent frames 
will be specially considered.  
Type 2:  Grown frames  only (a) Wood floors on every frame.  
(b) Steel floors on every frame.  
(c) Strap floors on every frame.  
(d) Angle floors on every frame.  Type 3:  Laminated frames only 
Type 4:  Steel frames only  (a) Steel plate floors at every frame.  
Types 5 and 6:  Grown, laminated or steel 
frames with l or 2 bent 
frames  (a) On grown and laminated frames as for Type 2.  
(b) On steel frames as for Type 4.  
(c) On bent frames as for Type 1 within 3/5L amidships. If D 
does not exceed 2.4 m no floors are required on bent frames 
outside 3/5L amidships.  
Type 7:  Grown, laminated or steel 
frames with 3 bent frames  (a) As for Types 5 and 6 but a floor as required for Type 1 is 
to be fitted to the middle -bent frame.  
  
23 ©TBS 2023 -All rights reserved   
 
 
 
 
©TBS 2023 -All rights reserved  24  
 
 
Figure 11: Typical floors  
*To be checked into centreline member where required by 5.2.5.1 .4 
5.2.6.3  Scantlings and construction  
5.2.6.3.1  The scantlings of floors are to be as given in Table 5 and the lengths of arms, etc., are to be 
 
25 ©TBS 2023 -All rights reserved  measured as shown in figure 11. At the ends of the craft the length of arms need not exceed one -
third the length of the frame.  
5.2.6.3.2  The cross -sectional area at the e nds of the arms is to be not less than half that given in Table 5 
for the middle line.  
5.2.6.3.3  Where bolts attaching the ballast keel pass through wood floors, the siding of the floors for the 
breadth of keel is to be not less than 3 times the bolt diameter. It ma y be tapered to the Rule 
siding at the ends of the floors.  
5.2.6.3.4  Angle steel floors are to be fitted on top of bent frames and it is recommended that this 
arrangement be adopted when angle floors are fitted to grown frames.  
5.2.6.3.5  Where angle floors are fitted to grown  frames it is recommended that they be fitted so that the 
frame fits into the bosom of the angle with a lug fitted to take the throat fastening.  
5.2.6.3.6  Steel plate floors are to be stiffened at the upper edge with a reverse angle, face flat or a flange 
having the same breath as the Rule angle. The thickness of flanged floors is to be increased by 
10 %. The bottom angle in way of the keel is to be 2.5 mm t hicker than the floor, and its flange is 
to be sufficient to take the ballast keel bolts or throat fastenings.  
5.2.6.3.7  In the machinery space of motor craft, steel plate floors are to be stiffened at the upper edge with 
a face flat and the thickness of the floors increased by 1 mm above tha t required by Table 5.   
©TBS 2023 -All rights reserved   26 Table 5: Floors for motor, sailing and auxiliary craft  
Depth, D. m Floors on grown or laminated frames  Floors on bent wood frames  Steel plate floors on grown or 
steel  frames, mm  
Motor  Sailing 
and 
auxiliary  Length of arms.  
mm Strap floors.  
mm Wood floors at 
middle line  Steel 
angle bar 
mm Length 
of arms 
mm Strap floors.  
mm Steel angle 
bar mm  For 3/5L 
amid -
ship At ends beyond 
3/5L amid -ship 
For 
3/5L 
amid -
ship Beyond 
3/5L 
amid -
ship At throat  At 
point  Moulding 
mm Siding 
mm At 
throat  At point  
1.5 1.8 380 250 25 xl0  20 x 10  55 25 30 x30 x5  250 25 x 6  15 x 6  25 x 25 x 5  150 x3  110 x3  
1.8 2.1 430 300 35 x 13  30 x10  75 35 35 x35 x6  300 25 x 9  17 x 6  25 x 25 x 5  190 x3  140 x 3  
2.1 2.4 480 350 45 x 16  40 x10  95 45 45 x45 x5  350 25 x12 19 x 6  30x30x5  230 x4  170x4  
2.4 2.7 530 390 50 x 19  45 x 10  115 55 50 x50 x5  390 27 x12  21 x 6  35 x35 x5  260 x4  190 x4  
2.7 3.0 580 430 55 x22 50 x 12  135 62 55 x55 x6  430 29 x 15  24 x6  40 x40 x4  280 x4  210 x4  
3.0 3.3 630 480 62 x25  53 x 14  155 70 65 x65 x7  480 32 x16  26 x6  40 x40 x4  300x5  230 x4  
3.3 3.6 680 530 70 x28  56 x 16  170 80 75 x75 x7  530 35 x17  29 x6  40 x40 x4  320 x5  240 x4  
3.6 3.9 730 570 75 x 31  60 x 18  185 90 80x80x7  - - - - 340 x6  250 x5  
3.9 4.2 780 620 80 x31  63 x20  200 100 90x75 x7  - - - - 360 x6  260 x5  
NOTE  
The Table scantlings of timber floors are based on a timber having a standard density of 720 kg/m3 and where timber of a different density is to be used the scantlings 
are to be modified in accordance with 5.1.4 
  
27 ©TBS 2023 -All rights reserved  Table 6: Floor fastenings for motor, sailing and auxiliary craft  
Depth, D, mm  Diameter of bolts in  throat, mm  Diameter of bolts at arms, mm  
Motor  Sailing and 
auxiliary  Grown 
laminated or 
steel frame  Bent frame  Grown 
laminated or 
steel frame  Bent frame  
1.5  1.8  8  6  6  6 
1.8  2.1  10  8  8  6 
2.1  2.4  12  8  8  6 
2.4  2.7  12  10  10  8 
2.7  3.0  14  12  12  8 
3.0  3.3  18  12  12  10 
3.3  3.6  20  12  12  10 
3.6  3.9  20  - 14  - 
3.9  4.2  20  - 16  - 
NOTES  
1. Throat to keel; not less than 2 bolts ( see 5.2.6.4.3 ). 
2. Arms to frames:  
3. Bolts when arm length does not exceed 250 mm,  
4. Bolts when arm length exceeds 250 mm.  
5.2.6.4  Fastenings  
5.2.6.4.1  The size of the floor fastenings are to be as given in Table 6.  
5.2.6.4.2  There are to be not less than three fastenings in each arm w here the length of arm does not 
exceed 250 mm or four when the arm is 250 mm or greater.  
5.2.6.4.3  The throat is to be attached to the wood keel by not less than two through bolts where practicable.  
5.2.7  Beam shelf and clamp, bilge stringers, breast hooks and bottom gird ers 
5.2.7.1  Beam shelf  
5.2.7.1.1  The cross -sectional area of beam shelf for 3/5L amidships is to be as given in Table  7.  Outside 
this length the area may be gradually reduced to the ends where it may be 25 % less than that 
amidships.  
5.2.7.1.2  The area of beam shelf determined from Table 7 is to be that clear of beams; the section removed 
for the beam end is not to impair the effi ciency of the shelf.  
5.2.7.1.3  Where the beam shelf is not fitted in one length, a plain glued scarph is to be arranged. Scarphs 
are to be suitably positioned in relation to joints in other longitudinal members and to hanging 
knees, etc. The face of the scarph is ge nerally to be in the vertical plane.  
5.2.7.1.4  Where there is a raised deck, it is recommended that the main beam shelf be carried to the ends. 
Where, however, this is not done suitable arrangements are to be made to maintain the 
longitudinal continuity of the shelf , and the frame scantlings in way may be required to be 
increased.  
5.2.7.1.5  The beam shelf is to be attached to each frame by one through fastening where the moulding of 
the shelf does not exceed 180 mm and by two through fastenings where the moulding exceeds 
180mm . The size of fastenings is given in Table 7.  
5.2.7.1.6  Where the framing is of Type 5, 6 or 7 ( see 5.2.5.2.1 ), chocks are to be fitted between the 
intermediate bent frames and the shelf.  
5.2.7.1.7  Lugs are to be fitted to steel frames to take the shelf fastenings.  
5.2.7.1.8  Where stee l frames are fitted in association with steel beams, a beam shelf is not required but a 
deck stringer plate; a sheer strake and a stringer angle of the scantlings given in the Table 15 are 
to be fitted. Beam knees are also to be provided in accordance with  5.2.10.5.2.  
5.2.7.1.9  For size of fastenings, see Table 7.  
5.2.7.2  Beam clamp  
5.2.7.2.1  In way of the mast in sailing and auxiliary craft, a clamp is to be fitted to the inboard side of the 
shelf with its upper surface faying closely to the underside  of the beams. Alternatively,  the clamp  
©TBS 2023 -All rights reserved  28 may be fitted below the shelf and it is to fay closely to the shelf and to the frames.  
5.2.7.2.2  The length of the clamp is generally to be not less than the breadth of the craft in way of the mast, 
and its cross -sectional area is to be not less than 75 % of the beam shelf area at the centre and 
may be tapered to 50 % of this section at the ends.  
5.2.7.2.3  The clamp is to be through fastened to the beams or frames as appropriate  
5.2.7.2.4  Where steel construction is adopted, see 5.2.10.5.6.  
5.2.7.3  Bilge stringer  
5.2.7.3.1  A bilge stringer is to b e fitted where the framing is Type 1 (bent only) or Type 7 (three bents 
between grown, laminated or steel), or where the length,  L, exceeds 9 .0 m for Types 2, 3, 5 and 
6. For steel construction (Type 4), see 5.2.7.3.9  
5.2.7.3.2  The cross -sectional area of bilge stri ngers for 3/5L amidships is to be as given in Table 7. Outside 
this length the area may be gradually reduced to the ends where it may be 25 % less than 
amidships. The greatest dimension of the stringer is to be fitted against the frames.  
5.2.7.3.3  Scarphs in the por t and starboard stringers are to be staggered and suitably positioned in relation 
to joints in other members. The face of the scarph in the stringer is to be cut parallel to the frames.  
5.2.7.3.4  Stringers are to be attached to each frame by one through fastening wh ere the moulding of the 
stringer does not exceed 180 mm and by two through fastenings when the moulding exceeds 180 
mm. 
5.2.7.3.5  Where the framing is of Type 5, 6 or 7 ( 5.2.5.2.1), chocks are to be fitted between the intermediate 
bent frames and the stringer.  
5.2.7.3.6  Lugs are to be fitted to steel frames to take the stringer fastenings.  
5.2.7.3.7  As an alternative to the fitting of a bilge stringer two or more side stringers may be fitted. Where 
two side stringers are fitted the cross -sectional area of each is to be no t less than 60 % of the 
Rule area for the bilge stringer.  
5.2.7.3.8  For size of fastenings, see Table 7 . 
5.2.7.3.9  For bilge stringers, etc., in steel construction, the arrangements are to be as follows: - 
(a) Where the framing is Type 4 (steel frames) a bilge stringer is to be fitted where the depth 
from top of floor to deck at side amidships exceeds 2.4m unless a cabin deck is fitted.  
(b) A side keelson is to be fitted when the half -breadth at the top of the floor amidships 
exceeds 2.4 m.  
(c) The scantlings of the bilge stringer and si de keelson are given in Table 7. These are to 
extend as far forward and aft as practicable.  
(d) Bilge stringers and side keelsons are to be welded to the frames or attached by frame lugs 
with not less than two rivets.  
Table 7: Beam shel f and bilge stringer scantlings and fastenings for motor, sailing and auxiliary craft  
Length
, L, m Cross -sectional 
area of beam -shelf, 
cm2 Cross -sectional 
area of bilge 
stringer, cm2 Diameter of bolts, mm,  Steel side 
keelson and 
bilge stringer 
angles, mm  
Sailing 
and 
auxiliary  Motor  Sailing 
and 
auxiliary  Motor  Arms of 
breast -
hook  Beam 
shelf 
stringers  Hanging 
knees   
6 29 32 25 22 8 6 6  
8 40 40 32 29 8 6 6  
10 50 50 40 35 8 6 6  
12 70 60 50 50 10 8 8  
14 90 80 65 60 12 8 8 60 x60 x 4.0  
16 110 100 80 70 12 8 8 60 x60 x 5.5  
18 130 110 90 85 12 10 10 65 x65 x 6.5  
20 150 130 105 100 14 12 12 75 x65 x 5.5  
22 170 150 120 110 14 12 12 75 x 65 x 6.5  
24 190 170 140 125 14 12 12 75 x 65 x 7.0   
29 ©TBS 2023 -All rights reserved  NOTE  
The Table scantlings for the beams shelf and bilge stringer are based on a timber having a standard density of 560 
kg/m3 and where timber of a different density is to be used the scantlings are to be modified in accordance with 5.1.4. 
5.2.7.4  Breast hooks  
5.2.7.4.1  The beam shelf and stringer ends are to be efficiently atta ched to the centreline construction. 
Breast hooks and transom quarter knees are to be fitted as necessary.  
5.2.7.4.2  The ends of the craft are to be suitably strengthened, and particular attention is to be given to this 
where there is a large overhang.  
5.2.7.4.3  For size of f astenings, see Table 7 . 
5.2.7.5  Bottom girders  
5.2.7.5.1  The engine seating’s are to be of substantial construction to suit the power of the machinery.  
5.2.7.5.2  The longitudinal girders forming the engine seating’s  are to extend as far forward and aft as 
practicable and are to be adequately supported by transverse floors and/or brackets.  
5.2.7.5.3  Additional side girders may be required in the machinery space and in the bottom of the craft 
forward.  
5.2.8  Watertight Bulkheads  
5.2.8.1  General  
5.2.8.1.1  Every vessel shall be provided with watertight bulkheads as required by Regulation 36 of 
Merchant Shipping (Small ships, Local Cargo Ship Safety, Small Ship Safety, Surveys and 
Inspection for Vessels Engaged on Local and Coastal Voyages, Inland Waters).  
Regulation 36:   
Subdivision of passenger vessels and certain cargo -passenger vessels  
(1) On: 
(a) passenger vessels 20m and above in length; and  
(b) passenger vessels and cargo -passenger vessels less than 20m in length, that are  certified to 
carry 50 p assengers or more and to operate in open waters;  
5.2.8.1.2  Watertight bulkheads may be constructed of timber or steel. Other materials shall be subject to 
special consideration by the overseeing authority . 
5.2.8.1.3  Watertight bulkheads shall be pierced to the least possible extent, and where they are pierced 
proper steps shall be taken to maintain their watertight integrity.  
5.2.8.2  Timber Bulkheads  
5.2.8.2.1  Timber bulkheads shall be constructed to the scantlings shown in Table 8. Such bulkheads shall 
have vertical stiffeners fastened into th e grounds and to the deck beams.  
5.2.8.2.2  The timber grounds shall be bedded into non -setting mastic or other material approved for this 
purpose and be through fastened to the hull planking.  
5.2.8.2.3  The planking on timber bulkheads may be fitted either into rabbets or on t o the face of the 
bulkhead grounds. It may also be fastened to the face of deep or web frames where such frames 
are fitted and fastened to the hull planking and are not less in size than the scantlings for web 
frames.  
5.2.8.2.4  Planked bulkheads shall be laid diagon ally with two equal thicknesses having a material 
acceptable to the Authority between these layers.  
Table 8: Timber bulkheads   
Planking  Stiffener  
Height of 
bulkhead  Double 
planked  Ply- wood  Stiffener 
spacing  Moulding  Siding  
m mm mm mm mm mm 
1.0 20 10 400 70 35 
1.5 30 15 400 85 45  
©TBS 2023 -All rights reserved  30  
Planking  Stiffener  
Height of 
bulkhead  Double 
planked  Ply- wood  Stiffener 
spacing  Moulding  Siding  
2.0 40 20 400 100 55 
2.5 50 25 450 115 65 
3.0 60 30 450 135 75 
3.5 70 35 450 150 85 
4.0 80 40 450 165 95 
NOTES  
1. The height of the bulkhead is to be measured from the top of the keel to the underside of the deck beam at the centre 
line of the vessel.  
2. Where stiffener spacing differs from the basic stiffener spacing shown in the Table planking thickness shall be 
increased and may be decreased for every increase or decrease respectively in the r esulting span between stiffeners 
as follows:  
(i) Planking -3 mm per 30 mm difference  
(ii) (ii) Plywood -3 mm per 50 mm difference.  
3. If the stiffener spacing shown in the table is not used then the stiffener scantlings are to be adjusted by maintaining 
the section modu lus of stiffener per millimetre of stiffener spacing  
4. In the case of a collision bulkhead the table planking thickness is to be increased by 25 % and the section modulus 
of the stiffener is to be not less than 1.25 times the table modulus.  
5. Where collision bulkhead stiffeners are glued and fastened to the bulkhead, the required increase, based on the 
section modulus will be specially considered.  
5.2.8.3  Steel  Bulkheads  
5.2.8.3.1  The scantlings of steel watertight bulkheads are given in Table 9.  
5.2.8.3.2  In collision bulkhead s the spacing of stiffeners is to be not greater than 460 mm,  
5.2.8.3.3  At the level of the decks below the upper deck, angles or flats are to be suitably attached to the 
bulkheads for taking the fastenings of the wood deck.  
5.2.8.3.4  Steel bulkheads are to be attached to woo d frames of the size required for grown frames or to a 
boundary angle of the size required for steel frames.  
Table 9: Bulkhead plating and stiffeners for motor, sailing and auxiliary craft  
Bulkhead plating and spacing of stiffeners  Stiffeners with free ends  
Depth of  
bulkhead at  
middle line  Thickness of 
plating, mm  Spacing of 
stiffener, mm  Overall length of 
stiffener, m  Height of upper deck above top of 
stiffener, m  
0 0.6 1.2 1.8 2.4 
Modulus, cm3 
1.5 2.5 300 1.5 2.5 4.6 6.6 8.7 11.0 
1.8 3.0 325 1.8 4.8 8.0 11.0 14.0 17.0 
2.1 3.5 350 2.1 8.0 13.0 17.0 22.0 27.0 
2.4 4.0 375 2.4 13.0 20.0 26.0 33.0 39.0 
2.7 4.5 400 2.7 20.0 29,0 37.0 46.0 55.0 
3.0 5.0 425 3.0 29.0 40.0 52.0 63.0 75.0 
3.3 5.0 450 3.3 40.0 55.0 70.0 85.0 - 
3.6 5.5 475 3.6 56.0 75.0 93.0 - - 
3.9 5.5 500 3.9 75.0 98.0 120.0  - - 
4.2 6.0 525 4.2 98.0 125,0  - - - 
4.5 6.0 550 4.5 125.0  160.0  - -- -- 
4.8 6.5 575 4.8 160.0  - - - - 
NOTES  
1. When the spacing of stiffeners differs from that given in the table, the thickness of the plating is to be modified at 
the rate of 0.5 mm for each 100 mm difference in spacing. The modulus of the stiffeners is to be modified in direct 
proportion to the stiffener spacing.  
2. The moduli given in the Table are  for unbracketed stiffening sections in association with plating.  
3. Where stiffening sections are bracketed at the top and bottom the Table modulus, corrected in accordance with 
Note 1, is to be multiplied by the factor, Ft. determined from the following formula: -  
31 ©TBS 2023 -All rights reserved  𝐹𝑡=0.8−ℎ
3.75(ℎ+𝑙) 
where  
h = height of upper deck above top of stiffener in metres.  
l = length of stiffener, in metres.  
5.2.9  Hull planking  
5.2.9.1  General  
5.2.9.1.1  The outside planking may be single skin (carvel or clinker), strip, do uble skin, single skin plywood 
or cold moulded laminations.  
5.2.9.1.2  The thickness for single skin carvel or strip construction is to be as given in Table 10.  
Table 10: Outside and deck planking for motor ,sailing  and auxiliary craft  
Length, L, m Basic thickness, mm  
6 19 
8 21.5 
10 24 
12 28 
14 32 
16 36 
18 39 
20 41.5 
22 43.5 
24 45.5 
NOTES  
1. The Table thicknesses of outside and deck planking are based on a timber having a standard density of 560 kg/m3 
and 430 kg/m3 respectively, and where timber of a different density is to be used the thickness is to be modified in 
accordance with 5.1.4. 
2. For frame and beam spacing corrections, see 5.2.9.1.3  and 5.2.11.1.3 . respectively.  
3. The basic thicknesses are applicable  to single skin carvel or strip outside planking and to a laid deck. For corrections 
for other types of construction, see 5.2. 9.1.4  for outside planking and 5.2.11.1.5, 5.2.11.1.6 and 5.2.11.1.7 for deck 
planking.  
5.2.9.1.3  Where the frame spacing differs from that  given in Table 5 the thickness of planking determined 
from Table 9 is to be modified as follows: - 
Type 1:  bent frames  1.5 mm per 25 mm difference  
 Other frame types  1.5 mm per 38 mm difference  
5.2.9.1.4  The thickness determined from Table 9, after correction for frame spacing and, except for 
plywood, density of timber, may be reduced for the type of planking as follows: - 
Clinker  10 percent  
Diagonal double skin  10 percent  
Cold moulded laminate  The reduction will depend on the framing or stiffening system 
adopted and will be a maximum of 25 % Single skin plywood  
5.2.9.2  Single skin  
5.2.9.2.1  Butts of the outside planking are to be spaced not less than 1 .2 m apart and no butts are to be in 
the same frame space u nless there are three strakes between, see Fig ure 12. The arrangement 
of butts at the ends of the craft is to be to the Surveyor's satisfaction.  
5.2.9.2.2  The butts in the garboard strake are to be kept clear of the keel scarph. Butts in the sheer strake  
are to be c lear of butts in the covering board.   
©TBS 2023 -All rights reserved  32 5.2.9.2.3  Butts in the planking are to be strapped or scarphed.  
 
Figure 12: Spacing of butts  
5.2.9.2.4  Wood or metal butt straps are to be arranged between the frames but a drainage space is to be 
left between the strap and the frame. The breadth is to be sufficient to overlap the adjacent planks 
by about 12 mm.  
5.2.9.2.5  Wood butt straps are to have the same thickness as the planking. Metal straps are to be not less 
than 1/6 of the planking thickness, see Figure 13. 
 
33 ©TBS 2023 -All rights reserved   
Figure 13: Typical butt straps on single skin hull planking  
 
5.2.9.2.6  The planking and the straps are to be through fastened. The size of the fastenings is to be as 
required by Table 10 for planking to frames, and the number is to be as follows: - 
Width of planking, mm  Number of fastenings  in each plank end  
Under 100  3 
100 and under 200  4 
200 and under 250  5 
5.2.9.2.7  The length of a scarph is to be not less than four times the thickness of the planking. The scarph 
is to be positioned on the frame, and glued and fastened to it.  
5.2.9.2.8  In sailing and auxiliary craft, the garboard and adjacent strakes are to be of increased width at the 
after end to give a reasonable plank fun, and the garboard strake is to be in as long a length as 
possible.  
5.2.9.2.9  Where, with planks of normal breadth, the length of snapped ends exceeds 250 mm, the planks 
are to be checked into the centreline structure ( see Fig ure 14). The sizes of the fastenings are to 
be as for the garboard strake ( see 5.2.9.2.11 ). 
 
©TBS 2023 -All rights reserved  34  
Figure 14: Connection of single skin planking to centreline structure (for normal breadth of planking)  
5.2.9.2.10  When strip planking is adopted, the top and bottom edges are to be rounded and hollowed 
respectively. Each plank is to be glued and edge fastened to the one below with non -ferrous 
fastenings , see Fig ure 15 Suitable stealer planks may be fitted to suit planking arrangements.  
5.2.9.2.11  The garboard strakes are to be screw fastened to the keel or hog. The screws are to be of the 
size required b y Table 10 for outside planking to Type 2 grown frames. They are to be reeled, and 
are to be spaced not more than twelve diameters apart in each row and are to enter the keel or 
hog to a depth at least equal to the thickness of the garboard. In way of dead woods a combination 
of dumps and screws may be used.  
5.2.9.2.12  The size and number of fastenings attaching the outside planking to the frames are to be as 
given in Table 10. The types of fastenings are dependent on the framing as follows: - 
Type 1:  Bent frames  All through fastenings  
Type 2:  Grown frames  Through fastenings to be arranged 
in way of beam shelf, bilge (or side) 
stringer, and tuck (in a sailing or 
auxiliary craft). The remainder may 
be screws  Type 3:  Laminated frames  
Type 4:  Steel frames  Nut and screw bolts  
Types 5, 6 and 7:  Grown, laminated or 
steel frames with bent 
frames between  Bent, as for Type 1 Grown and 
laminated, as for Types 2 and 3 
Steel, as for Type 4  
5.2.9.2.13  Where frames are increased in way of the mast (see 5.2.5.3.6), they are to be throu gh fastened 
 
35 ©TBS 2023 -All rights reserved  throughout.  
5.2.9.3  Double skin  
5.2.9.3.1  Double skin planking may be arranged as follows: - 
(a) Both diagonal,  
(b) Inner diagonal, outer fore and aft,  
(c) Both fore and aft.  
5.2.9.3.2  The outer skin is to be approximately 3/5 of the total thickness, and the diagonal planking is to be 
at approximately 45°.  
5.2.9.3.3  The inner skin is to be either screw or nail fastened to the frames, and the outer skin is to be 
through fastened to the frames. In arrangements 5.2.9.3.1 (a) and (b) through fastenings are to 
be fitted at the plank crossings, and in 5.2.9.3.1 (c) the inner skin is to be screw fastened to the 
outer between frames , see Fig ure 15. 
 
Figure 15: Strip planking  
 
 
©TBS 2023 -All rights reserved   36 Table 11: Fastenings for outside end deck planking in motor, sailing end auxiliary craft  
Planking 
thickness, 
mm Size of fastenings  Number of fastenings per plank  
Outside planking  Deck planking  Width of plank  
Grown, laminated or steel frames  Bent frames  Wood 
screws 
diameter  Bolt, 
mm Under 
100 
mm 100 mm 
and 
under 
150mm  150 mm 
and under 
180mm  180 mm 
and under 
205mm  205mm 
and under 
225mm  Bolt, 
mm Wood 
screws 
diameter  Cooper bolt 
nails*size  Cooper bolt 
nails size  
mm gauge  mm gauge  mm gauge  mm gauge  
19 6 5 10 4.5 7 2.5 12 4.5 8 5 2 2 3 3 3 
20.5 6 5 10 5 6 3 11 5 10 5 2 2 3 3 3 
22 6 5 10 6,5 3 3.5 10 5 10 6 2 2 3 3 3 
23.5 6 5 10 6.5 3 3.5 10 5 10 6 2 2 3 3 3 
25 6 5.5 12 6.5 3 3.5 9 5 10 6 1 2 2 3 3 
26.5 6 5.5 12 6.5 3 3.5 9 5.5 12 6 1 2 2 3 3 
28 6 5.5 12 6.5 3 4.5 7 5.5 12 6 1 2 2 3 3 
29.5 6 5.5 12 6.5 3 4.5 7 5.5 12 6 1 2 2 3 3 
31 8 6.5 14 7.5 1 5 6 5.5 12 6 1 2 2 3 3 
32.5 8 6.5 14 7.5 1 5 6 6.5 14 8 1 2 2 3 3 
34 8 6.5 14 7.5 1 5.5 5 6.5 14 8 1 2 2 3 3 
36.5 8 7 16 7.5 1 5.5 5 6.5 14 8 1 2 2 3 3 
37 8 7 16 7.5 1 5.5 5 6.5 14 8 1 2 2 2 3 
38.5 8 7 16 9.5 3/0 5.5 5 7 16 8 1 2 2 2 3 
40 10 8 18 9.5 3/0 6 4 7 16 8 1 2 2 2 3 
41.5 10 8 18 9.5 3/0 6 4 7 16 8 1 2 2 2 3 
43 10 8 18 9.5 3/0 - - 8 18 10 1 2 2 2 3 
44.5 10 8 18 9.5 3/0 - - 8 18 10 1 2 2 2 3 
46 12 8.5 20 11 5/0 - - 8 18 10 1 2 2 2 3 
47.5 12 8.5 20 11 5/0 - - 8 18 10 1 2 2 2 3 
49 12 8.5 20 11 5/0 - - 8 18 10 1 2 2 2 3 
50.5 12 10 24 12.5 7/0 - - 8.5 20 12 1 2 2 2 3 
52 12 10 24 12.5 7/0 - - 8.5 20 12 1 2 2 2 3 
*·For grown or laminated frames only.  
NOTES  
1. The diameter of the wood screws given in the Table is the nominal diameter of the unthreaded shank.  
2. The gauge of wood screws given in the Table is British Standard Gauge, and that of copper boat nails is Imperial Standard Wire Gauge.  
  
37 ©TBS 2023 -All rights reserved  5.2.9.3.4  In arrangements 5.2.9.3.1 (a) and (b) oiled calico dipped in linseed oil or an equivalent membrane 
is to be laid between the skins, and in 5.2.9.3.1 (c) it is recommended that resorcinol glue be used 
between the skins.  
5.2.9.3.5  The arrangement at the gunwale is to be such as to ens ure that the covering board can be made 
watertight.  
Typical methods are shown in Fig ure 16. 
 
 
©TBS 2023 -All rights reserved  38  
Figure 16: Arrangement of fastening in double skin hull planking  
 
Figure 17: Detail of gunwale for double skin planking  
5.2.9.4  Plywood planking  
5.2.9.4.1  Plywood is to be fitted in as large panels as practicable having due regard to the form of the craft. 
Panel butts are to be staggered between the bottom, side and deck and arranged clear of the 
mast, ballast keel and e ngine seating.  
5.2.9.4.2  The width of longitudinal seam landings on the centreline structure, chine and gunwale members 
and on any longitudinal stringers is to be not less than that required by Table 11. Seams are to 
be glued and fastened with one or two rows of fas tenings ( see Table 11 ), and arranged to give 
maximum spacing of fastenings of 50 mm.  
5.2.9.4.3  Butts and seams are to be scarphed or strapped where necessary. The length of a scarph is to 
be not less than 8 times the hull thickness. The scarph is to be glued and, if  made in situ, fitted 
with a backing strap of a width not less than 10 times the hull thickness. The strap is to be glued 
and fastened to the hull with two rows of fastenings of the size given in Table 12 and spaced 
about 8 times the hull thickness.  
5.2.9.4.4  Butt s traps are to be of the width given in Table 13 and the same thickness as the hull planking. 
The strap is to be glued and double or treble fastened to the hull planking. The size of fastenings 
is to be as given in Table 13  
5.2.9.4.5  The hull planking is to be attache d to the frames by fastenings of the size given in Table 11, 
spaced generally not more than 75 mm apart.  
5.2.9.5  Hull sheathing  
 
39 ©TBS 2023 -All rights reserved  5.2.9.5.1  Whilst it is not a requirement of the Rules that the outside planking be sheathed, if this is done it 
must be efficiently carried out to the Surveyor's satisfaction.  
5.2.9.5.2  Copper sheathing should be bedded on bitumastic treated paper or felt. The sheets are to be 
dressed to ensure that the sheathing is in close contact with the bedding. They are to overlap 
each other by about 22 mm; the vertic al laps are to face aft and the horizontal laps are to face 
upwards. Fastening is to be by coppering nails spaced at not more than 40 mm at the sheet edges. 
In addition, the panel is to be tack fastened at spacings of not more than 75 mm vertically and 
150 mm horizontally. The sheathing is to be stopped short of the rabbet line and a wrapper piece 
fitted.  
5.2.9.5.3  Where synthetic sheathing is used, care is to be taken to ensure that the moisture content of the 
timber is as low as is practicable. All seams and fasten ing holes to be splined or dowelled or 
stopped with a compound which is compatible with the manufacturer's recommendations. 
Wherever possible, the sheathing is to be fitted around the wood keel and deadwood before the 
ballast keel is fitted.  
Table 12: Plywood planking: overlaps and fastenings for motor, sailing and auxiliary craft  
 Minimum breadth of landing between  Fastenings  
Plywood  
planking  
thickness,  
mm Hull planking and 
keel or chine, mm   Hull or deck planking 
and shelf or 
longitudinal, mm  Wood screws  Cooper boat 
nails, gauge  
Gauge  Diameter  
mm  
6 25 
Single 
fastened  
Single 
fastened  25 8 4.2 10 
8 28 28 10 4.9 10 
10 32 32 10 4.9 8 
13 44 
Double 
fastened  35 12 5.6 8 
16 50 
Double 
fastened  44 12 5.6 6 
19 57 50 14 6.3 6 
22 63 57 14 6.3 3 
25 63 57 16 7.0 3 
NOTES  
1. The gauge of wood screws given in the Table is British Standard Gauge. and that of copper boat nails is Imperial 
Standard Wire Gauge.  
2. The diameter of the wood screw is the nominal diameter of the unthreaded shank.  
Table 13: Plywood planking: butts and butt straps for motor , sailing and auxiliary craft  
Plywood planking 
thickness,  
mm Breath of butt 
strap, mm  Wood screws  Cooper boat nails, gauge  
Gauge  Dia, mm  
6 150 Double 
fastened  8 4.2 10 
8 175 10 4.9 10 
10 200 10 4.9 8 
13 250 12 5.6 8 
16 280 12 5.6 6 
19 330 Triple 
fastened  14 6.3 6 
22 355 14 6.3 3 
25 380 16 7.0 3 
NOTES  
1. The gauge of wood screws given in the Table is British Standard Gauge. and that of copper boat nails is Imperial 
Standard Wire Gauge.  
2. The diameter of the wood screw is the nominal diameter of the unthreaded shank.  
5.2.10  Beams  
5.2.10.1  Scantlings -Timber  
5.2.10.1.1  The scantlings of ordinary beams, half beams and strong beams are to be not less than those 
given in Table 14.   
©TBS 2023 -All rights reserved  40 5.2.10.1.2  Where the actual beam spacing differs from that given in Table 14, the strength of ordinary and 
half beams is to be modified in direct proportion, i.e.  
Actual (sm2) = Table (sm2) x 𝑎𝑐𝑡𝑢𝑎𝑙  𝑠𝑝𝑎𝑐𝑖𝑛𝑔
𝑡𝑎𝑏𝑙𝑒  𝑠𝑝𝑎𝑐𝑖𝑛𝑔 
where s and m are the siding and moulding, respectively; the Table siding is to be that after correction for 
density. see 5.1.4. 
5.2.10.1.3  Where laminated beams are fitted their siding may be reduced by 15 %. 
5.2.10.1.4   Strong beams are to be fitted at ends of openings when two or more beams are cut. They may 
also be required to be fitted in way of the mast.  
5.2.10.2  End attachments  
5.2.10.2.1  All beams are to be fastened to the shelf by dovetails or dowels , see Fi gure. 18. 
5.2.10.2.2  As an alternative to 5.2.10.2.1, where a plywood deck is fitted the beams need not be dovetailed 
or dowelled but may be carried past the shelf and checked over it. The depth of the check is to 
be about one -quarter of the depth of the beam and the beam is to be screw or dump fastened to 
the shelf.  
5.2.10.2.3  Hanging knees are to be fitted as required by Table 14 and are to be arranged at the mast and 
other strong beams to give a suitable disposition over the length of the craft.  
5.2.10.2.4  Hanging knees may be steel straps, flanged plates, ang le bar, or grown or laminated timber.  
5.2.10.2.5  The dimensions of strap -hanging  knees are given in Table 14 but at the ends of the craft the 
length of arms need not exceed one -third of the length of the frame or beam. Angle knees are 
to have equivalent strength.  
5.2.10.2.6  The minimum moulding at the throat of grown or laminated knees is to be 60 % or 40 %, 
respectively, greater than that required by Table 5 for ordinary grown frames at the heel.  
5.2.10.2.7  Each arm is to be connected to the beam and to the frame by four bolts of the diamet er given in 
Table 7. The bolts need not pass through the deck or outside planking.  
5.2.10.2.8  Bulkheads of substantial construction glued and screwed to the beams and frames will be 
accepted in lieu of hanging knees.  
5.2.10.2.9  Lodging knees are to be fitted to the beams in way  masts and at ends of deck openings unless 
a plywood deck is fitted.  
 
Figure 18: Dowel fastening of beam at shelf  
5.2.10.3  Local reinforcements  
5.2.10.3.1  The beams and deck are to be suitably strengthened in way of masts, coachroof ends, windlass, 
cleats, sheet winches etc. Where a mast is stepped on the deck the structural arrangements will 
be specially considered.  
5.2.10.3.2  All deck openings are to be properly fram ed with carlings fitted to receive the half beams.  
5.2.10.4  Cabin deck  
 
41 ©TBS 2023 -All rights reserved  5.2.10.4.1  Where the depth amidships from top of wood keel to top of beam at side amidships is 3 m or 
greater, cabin deck beams are to be fitted. The strength of these beams is to be at least 60 % of 
that required for upper deck beams, and the beams are to be efficiently attached to the craft's 
side.  
5.2.10.5  Steel construction  
5.2.10.5.1  Where steel beams are fitted, steel deck stringer plates and tie plates of dimensions given in 
Table 14 are to be arranged.  
5.2.10.5.2  The scantlings o f steel beams are given in Table 15. Where the spacing differs from that given 
in the Table the section modulus is to be modified in direct proportion. The Table scantlings apply 
over the midship 3
5L. Outside this, the thickness may be reduced by 10 %. Half beams are to be 
of the size required by the Table for the same length with one row of pillars and are to be attached 
to the carlings or coaming plates.  
5.2.10.5.3  Cabin deck beams are to be fitted where the depth amidships from top of floor to top of beam at 
side i s 3.2 m or greater. Beam knees are to be fitted on alternates and the remaining beams are 
to be fastened by lugs to the frames.  
5.2.10.5.4  Beam knees are to have arms not less than 21
2 times the depth of the beam, a distance across 
the throat of not less than 60 % of the length of the arms and a thickness as given in Table 15  
5.2.10.5.5  Strong beams are to be fitted in accordance with 5.2.10.1.4.  
5.2.10.5.6  Where masts are wedged to the deck the arrangements in way of the mast are to include the 
following: - 
(a) Mast deck plates of a length and  breadth of not less than three times the diameter of the mast 
hole, and a thickness equal to that of the stringer plate required by Table 15  
(b) Two diagonal tie plates, of the size given in Table 15 for tie plates, are to be fitted on the 
beams each side of the craft.  
(c) A collar is to be fitted around the opening to take the wedges.   
©TBS 2023 -All rights reserved   42 Table 14: Beams and hanging knees for motor, sailing and auxiliary craft  
Length 
of 
beam, 
m Spacing 
of 
ordinary 
beams 
centre to 
centre, 
mm Ordinary beams 3/5L amidship  Ordinary beams beyond 3/5L 
amidship, half beam throughout  Beams in way of masts and at ends 
of deck openings  Strap hanging knees to deck beams  
At middle  At ends  At middle  At ends  At middle  At ends   Length of arm, mm  At 
throat, 
mm At point, 
mm Siding, 
mm Mouldin
g, mm  Siding
, mm  Mouldin
g, mm  Sidin
g, 
mm Mouldin
g, mm  Sidin
g, 
mm Mouldin
g, mm  Sidin
g, 
mm Mouldi
ng, 
mm Siding, 
mm Mouldin
g, mm  Number 
on each 
side For 3/5L 
amidshi
p Beyond 
3/5L 
amidshi
p 
1.8 250 30 45 30 30 26 33 26 26 39 55 39 39 3 300 240 22 x 8  19 x 4  
2.1 275 36 53 36 36 32 40 32 32 46 65 46 46 4 325 260 22 x10  22x 4  
2.4 300 41 60 41 41 36 45 36 36 52 74 52 52 4 350 280 25 x 
12 22x 6  
2.7 325 46 66 46 46 40 50 40 40 58 83 58 58 5 375 300 30 x16  25 x 6  
3.0 350 51 72 51 51 43 54 43 43 63 90 63 63 5 400 320 34 x19  30x 6  
3.3 375 55 78 55 55 46 58 46 46 68 97 68 68 6 425 340 38 x19  35 x 6  
3.6 400 59 83 59 59 50 63 50 50 73 104 73 73 6 450 360 42 x22  40 x 8  
3.9 425 62 88 62 62 53 66 53 53 77 110 77 77 7 475 380 46 x22  40 x 8  
4.2 450 66 94 66 66 56 70 56 56 82 117 82 82 7 500 400 50x25  45 x 8  
4.5 475 69 99 69 69 58 74 58 58 86 124 86 86 8 525 420 52x25  45 x 8  
4.8 500 72 103 72 72 61 78 61 61 90 129 90 90 8 550 440 55 x27  50 x 10  
5.1 525 75 108 75 75 63 82 63 63 94 135 94 94 9 575 460 58 x27  50 x 11  
5.4 550 79 112 79 79 65 86 65 65 98 140 98 98 9 600 480 61 x30  50 x 11  
5.7 575 82 117 82 82 67 91 67 67 102 146 102 102 10 625 500 64 x30  52 x12  
6.0 600 85 121 85 85 69 96 69 69 107 151 107 107 10 650 520 67 x30  52 x12  
6.3 625 88 125 88 88 70 100 70 70 112 156 112 112 11 675 540 70x33  54x14  
6.6 650 91 130 91 91 71 105 71 71 119 163 119 119 11 700 560 72 x33  54 x14  
6.9 675 96 137 96 96 73 112 73 73 127 172 127 127 12 725 580 74 x33  57 x16  
7.2 700 102 145 102 102 75 120 75 75 135 180 135 135 12 750 600 78 x36  57 x16  
NOTES  
1. The length of a wood beam is to be measured amidships to the inside of the beam shelf.  
2. The Table scantlings of timber beams are based on a timber having a standard density of 560 kg/m3 and where timber of a different density is to be used the 
scantlings are to be modified  in accordance with 5.1.4. 
3. Where the beam spacing differs from that given in the Table, sm2 is to be modified in direct proportion , see 5.2.10.1.2 . 
43 ©TBS 2023 -All rights reserved  4. The siding of a laminated beam may be reduced by 15 %. 
Table 15:Longitudinal steel items for motor , sailing and auxiliary craft  
Length, m  Upper deck 
sheerstrake 
and stringer 
plate 3/5L 
amidship, mm  Upper deck 
sheerstrake  and 
stringer plate at 
ends and cabin 
deck stringer 
plate, mm  Upper deck 
tie plates, 
mm Upper deck 
stringer 
angle, mm  cabin deck 
tie plates, 
mm cabin deck 
stringer 
angle, mm  
10 220 x3.5  170 x3.5  100 x 3.5  45 x 45 x 3.5  - - 
12 250 x3.5  200 x3.5  100 x 3.5 45 x.45 x.4  - - 
14 290 x3.5  230 x3.5  115 x 3.5  50 x.50.x.4  - - 
16 335 x4  240 x4  120 x 4  50 x.50.x 4.5  75 x.4  50 x 50 x4  
18 375 x4.5  250 x4  130 x 4.5  50 x 50 x 5  85 x.4  50 x 50 x 4  
20 410 x4.5  280 x4  140 x 4.5  50 x 50 x 5  90 x.4  55 x 55 x.4  
22 455 x5  300 x4.5  150 x 5  55 x 55 x 5.5  100 x 4.5  60 x 60 x.4  
24 500 x5.5  325 x4.5  150 x 5.5  60 x 60 x 5  110 x 4.5  60 x 60 x 4.5  
Table 16: Steel angle beams at upper and cabin decks for motor, sailing and auxiliary craft  
Length 
of 
beam, 
m Spacing 
of 
beams, 
mm Upper deck beams, mm  Upper deck beams, mm  
Without pillars  Thickn
ess of 
knee  With one row 
of pillars  Thic
knes
s of 
knee  Without pillars  Thick
ness 
of 
knee  With one 
row of pillars  Thick
ness 
of 
knee  
2.4 305 65 x 50 x 5 4 - - 65 x 50 x 3.5  3.5 - - 
2.7 330 65 x 50 x6  4 - - 65 x 50 x 4  4 - - 
3.0 355 70 x 55 x6  4.5 - - 65 x 50 x 4.5  4 - - 
3.3 380 75 x 65 x 6.5  4.5 - - 65 x 65 x 5.5  4.5 - - 
3.6 405 85 x 65 x6.5  5 50 x 50 x 5  4 65 x 65x 7  4.5 40 x40 x 4.5  3.5 
3.9 430 90 x 65 x7  5 65 x 50 x4  4.5 75 x 65x 6  5 50 x40 x 3.5  4 
4.2 455 100 x 65 x6.5  5,5 65 x 50 x 4.5  4.5 75 x 65 x6.5  5 50 x50 x.4  4 
4.5 470 100 x 65 x7  6 65 x 50 x 5  5 75 x 65 x7.5  5.5 50 x50 x 4.5  4.5 
4.8 482 110 x 65 x7.5  6 65 x 60 x 5.5  5 85 x 65 x7  5.5 65 x50 x 4  4.5 
5.1 495 125 x 65 x 7.5  6.5 65 x 65 x 6  5.5 100 x 65 x5  6 65 x50 x 4.5  5 
5.4 508 135 x 65 x 7.5  6.5 75 x 65 x 5.5  5,5 100 x 65 x7  6 65 x50 x 5  5 
5.7 520 145 x 65 x 7.5  7 75 x 65 x6  6 110 x 65 x7.5  6,5 65 x50 x 5.5  5.5 
6.0 532 140 x 75x10  7 85 x 65 x 5  6 120 x 70 x 7.5  6.5 70 x60 x 5.5  5.5 
6.3 545 140 x 75 x12  7.5 90 x 75 x6.5  6.5 135 x75 x7.5  7 75 x65 x 6  6 
6.6 558 150 x 75x12  7.5 95 x 75 x7,5  6.5 140 x 75x 8  7 75 x65 x 6.5  6 
6.9 570 165 x 75 x12  8 100 x 75 x 8  7 145 x75 x 8.5  7.5 85 x 65 x6.5  6.5 
7.2 585 175 x 75 x12  8 100 x75 x 9  7 160 x 75 x 8.5  7.5 95 x65 x 6.5  6.5 
NOTES  
1. The length of a steel angle beam is to be measured to the toe of the frame amidships.  
2. Where the beam spacing differs from that given in the Table. The section modulus (without plating) is to be 
modified in direct proportion.  
5.2.11  Deck planking  
5.2.11.1  General  
5.2.11.1.1  Decks may consist of: - 
(a) Laid planks,  
(b) Plywood,  
(c) Plywood sheathed with a laid deck.  
5.2.11.1.2  The thickness of laid deck is to be as given in Table 10  
5.2.11.1.3  Where the beam spacing differs from that given in Table 14, the Table thickness is to be modified 
at the rate of 1 .5 mm per 50 mm difference.  
5.2.11.1.4  Where teak or other approved timber having a density exceeding 720 kg/m3 is used the thickness  
©TBS 2023 -All rights reserved  44 may be reduced by 12 %. 
5.2.11.1.5  Where plyw ood is used the thickness may be reduced by 30 %. 
5.2.11.1.6  Where plywood is sheathed with a laid deck the combined thickness may be 30 % less than the 
thickness in Table 10 provided that: - 
(a) the combined density of the plywood and sheathing is not less than 430 kg/m3, 
(b) the thickness of the plywood is not less than 30 percent of the combined thickness and in no 
case is less than 6 mm, and  
5.2.11.1.7  where the laid planking is less than 19 mm, the seams are filled with an approved flexible seam 
compound,  
5.2.11.1.8  Where the deck is covered wit h canvas, nylon, glass reinforced plastics or other approved 
sheathing, the thickness may be reduced by 1.5 mm.  
5.2.11.1.9  All exposed canvas seams are to be sewn and not overlapped and tacked. Securing of canvas 
by tacks should be used only where the edges are prote cted by listings, etc. The canvas is to be 
suitably bedded to the deck.  
5.2.11.2  Laid decks  
5.2.11.2.1  Butts of the deck planking are to be spaced not less than 1 .2 m apart and no butts are to be in 
the same transverse plane unless there are three strakes between.  see Fig ure12. 
5.2.11.2.2  The material for laid decks is to be quarter sawn.  
5.2.11.2.3  Butts are to be arranged on a beam and are to be of the scarph or caulked lip type unless the 
siding of the beam is sufficient to allow a caulked square butt to be used. see Fig ure 19. 
5.2.11.2.4  Deck planks a re to be attached to the beams by either screw fastenings from above, or side 
fastening by nails , see Fig ure 20. 
5.2.11.2.5  Where the beam spacing has been increased it may be necessary to fit horizontal dowels in the 
planking between the beams.  
5.2.11.2.6  The number and size o f screws are to be as given in Table 11. Deck covering boards are to be 
screw fastened to the sheer strake and beams. The screws to the sheer strake are generally to 
be spaced not more than 12 diameters apart.  
5.2.11.2.7  Where steel beams are fitted, the fastenings a re to be either nut and screw bolts or round head 
wood screws fitted from the underside of the beams. The number and size of bolts or screws are 
to be as given in Table 11.  
5.2.11.3  Plywood decks  
5.2.11.3.1  Plywood decks are to be fitted in panels as large as practicable.  
5.2.11.3.2  Butts are to be clear of those in the side planking and are not to be placed in the vicinity of the 
mast. They are to be on a strong beam or are to be strapped.  
5.2.11.3.3  Seams are to be strapped or scarphed or may be arranged on a longitudinal member having a 
width su fficient to give a landing of not less than that required by Table 12. Butts and seams are 
to be sealed watertight.  
5.2.11.3.4  Plywood decks are to be glued or bedded to the beams and at the deck edges. They are also to 
be fastened to the beams and at the edges by sc rews or barbed nails, as required by Table 12. 
The fastenings in beams and butts landing on structural members are to be as required for deck 
edges. If a strap is fitted, it is to be as required by 5.2.9.4.4 for hull plywood planking.  
5.2.11.3.5  Where plywood decks a re laid on steel beams, liners are to be fitted where stringer and tie plates 
are used. Liners are to be the same width as the beam and the same thickness as the plates.  
5.2.11.4  Plywood sheathed with laid deck  
5.2.11.4.1  Plywood decks sheathed with a laid deck are to comply with the requirements of 5.2.11.3.1 to 
5.2.11.3.3.  
5.2.11.4.2  Where thickness of the laid sheathing on plywood decks exceeds 50 % of the total thickness, the 
requirements of 5.2.11.2.1 and 5.2.11.2.2 are to be complied with. The sheathing is to be 
fastened through the plywood to the beams as for a laid deck , see 5.2.11.2.4  to 5.2.11.2.6.  
5.2.11.4.3  Where the laid sheathing is less than 50 % of the total thickness the butts are to be suitably  
45 ©TBS 2023 -All rights reserved  positioned, and the fastenings may pass through the plywood only and are to be  in accordance 
with 5.2.11.3.4.  
5.2.11.4.4  The laid sheathing is to be glued to the plywood with a resorcinol glue.  
 
Figure 19: Butts of deck planking  
 
 
©TBS 2023 -All rights reserved  46  
Figure 20: Deck fastening (laid decks)  
5.2.11.5  Watertightness  
5.2.11.5.1  Laid decks are to be caulked and payed or an acceptable deck seaming compound, applied in 
accordance with the manufacturers' recommendations, may be used. Wood dowels are to be 
glued.  
5.2.11.5.2  All weather decks are to be hose tested on completion.  
5.2.11.6  Deck fittings  
5.2.11.6.1  Fittings fixed to the deck are to be bedded on a suitable mastic compound to maintain the 
watertightness of the deck.  
5.2.11.6.2  It is recommended that in way of heavy fittings such as windlasses, winches, fairleads, etc., the 
deck planking and the fasten ing holes be coated with a suitable wood preservative prior to the 
application of the mastic.  
5.2.11.6.3  Guard rail stanchions are to be bedded on a suitable mastic compound and are to have not less 
than three fastenings through the palm, one of which is to be a thro ugh fastening.  
5.2.12  Pillars or Stanchions  
5.2.12.1  Pillar Load  
The load on a pillar is to be obtained from the following equation:  
w  =0.715 bhs  tonnes  
where:  
w  = load in tonnes  
 
47 ©TBS 2023 -All rights reserved  b  = mean breadth in metres of area supported  
s  =  spacing of pillars in metres  
h  = heig ht in metres above the deck supported, as defined below:  
(a) h for a pillar below an exposed deck on which cargo is carried is the distance from the deck supported, 
to a point 3.65 metres above the exposed deck. Where it is intended to carry deck cargoes in excess 
of 2640 kg /m2 this head is to be increased in proport ion to the added loads which will be imposed on 
the structure.  
(b) Where tween deck  cargo is carried and its mass is greater or less than 2640 kg /m2,h is also to be 
suitably adjusted.  
(c) h for a pillar below the freeboard deck is to be measured to a point not less than 0.02 L + 0.75 metres 
above the freeboard deck.  
(d) h for a pillar below the superstructure deck is to be measured to a point not less than 0.02 L + 0.50 
metres above the superstructure deck.  
5.2.12.2  Permissible Load  
(a) The permissible load pillar can carry is to be equal to or greater than the pillar load was determined 
above  (5.2.12.1) . The permissible load may be obtained from the equation:   
𝑤𝘢=𝐴
1000(𝑙−17(𝑙
𝘢))𝑡𝑜𝑛𝑛𝑒𝑠  
where:  
wa = Permissible load on the pillar in tonnes  
A = Area of the pillar in square mil limetres  
l = The unsupported length of the pillar in metres  
a = The diameter of a circular pillar or the shorter side of a rectangular pillar in millimetres.  
Table 17 gives pillar loadings for a representative selection of round and rectangular pillars.  
Table 17: Permissible load on timber pillars  
Permissible load on timber pillars  
a (mm)  Unsupported length of pillar (m)  
Rectangular section  Round section  
1 2 3 4 1 2 3 4 
50 1.7 0.8   1.3 0.6   
60 2.6 1.6 0.5  2.0 1.2 0.4  
70 3.7 2.5 1.3  2.9 2.0 1.0  
80 5.0 3.7 2.3 1.0 4.0 2.9 1.8 0.8 
90 6.6 5.0 3.5 2.0 5.2 4.0 2.8 1.6 
100 8.3 6.6 4.9 3.2 6.5 5.2 3.8 2.5 
110 10.2 8.4 6.5 4.6 8.0 6.6 5.1 3.6 
120 12.4 10.3 8.3 6.2 9.7 8.1 6.5 4.9 
130 14.7 12.5 10.3 8.1 11.5 9.8 8.1 6.3 
140 17.2 14.8 12.5 10.1 13.5 11.7 9.8 7.9 
150 20.0 17.4 14.9 12.3 15.7 13.7 11.7 9.7 
160 22.9 20.2 17.4 14.7 18.0 15.8 13.7 11.6 
170 26.0 23.1 20.2 17.3 20.4 18.2 15.9 13.6 
180 29.3 26.3 23.2 20.2 23.0 20.6 18.2 15.8 
190 32.9 29.6 26.4 23.2 25.8 23.3 20.7 18.2 
200 36.6 33.2 29.8 26.4 28.7 26.1 23.4 20.7 
NOTE:  
In the above table (a) is the shorter side of a rectangular pillar or the diameter of a circular pillar in millimeters . 
5.2.12.3  The scantlings of pillars and stanchions of a material other than timber shall be determined  
©TBS 2023 -All rights reserved  48 from the appropriate calculations.  
5.2.12.4  Pillars or stanchions may be placed directly under beams, deck opening corners or deck 
longitudinals, The spacing of pillars fitted under longitudinals between bulkheads shall not 
exceed 5 times the beam spacing = 500 mm in the fore and aft direction nor shall they be 
placed more than  25 % of the beam from the vessel's centreline.  
5.2.12.5  Supports under pillars or stanchions are to be of sufficient strength to distribute the loads 
effectively.  
5.2.13  Engine Seating  
The engine seating is to be of dimensions commensurate with the power of the machinery fitted thereto. 
They should  
(i) be of a length not less than twice the distance between the extreme holding down bolts;  
(ii) distribute the load over as many transverses as possible;  
(iii) terminate on a substantial transverse member; and  
(iv) be checked over and se curely fastened through all transverse floors and the hull planking.  
5.2.14  Coachroofs and deckhouses  
5.2.14.1  General  
Coachroofs and deckhouses are to be substantially constructed and efficiently connected to the carlings 
and beams.  
5.2.14.2  Coachroofs  
5.2.14.2.1  The scantlings of a coachro of are to be as given in Tables 18 and 19.  
Table 18: Coachroof coaming and deck thicknesses for motor, sailing and auxiliary craft  
Length, L, m Coaming thickness, mm  Coach roof deck thickness, mm  
6 17 13 
8 19 15 
10 22 17 
12 24 19 
14 26 22 
16 29 24 
18 32 26 
NOTES  
1. The Table thickness of coachroof coamings and deck are based on a timber having a standard density of 
560 kg/m3 and 430 kg/m3, respectively, and where timber of a different density is to be used the thickness 
is to be modified in accordance with 5.1.4. 
2. Where the coachroof  coaming or deck is of plywood the Table thickness may be reduced by 30 %. 
3. If the deck is covered with canvas or other approved sheathing the Table thickness may be reduced by 1.5 
mm. 
4. Where the beam spacing differs from that given in Table 19, the deck thi ckness is to be modified at the rate 
of 1.5 mm per 50 mm difference.  
Table 19: Coachroof and deckhouse beams for motor, sailing and auxiliary craft  
Length of 
beam, m  Spacing 
centre to 
centre, mm  At middle of beam  At ends of beam  
Siding, mm  Moulding, mm  Siding, mm  Moulding, mm  
1.2 255 28 41 28 28 
1.5 280 30 44 30 30 
1.8 305 34 48 34 34 
2.1 330 38 53 38 38 
2.4 355 41 57 41 41 
2.7 380 43 60 43 43 
3.0 405 44 63 44 44 
3.3 430 44 65 44 44 
3.6 455 46 68 46 46 
3.9 480 48 71 48 48  
49 ©TBS 2023 -All rights reserved  Length of 
beam, m  Spacing 
centre to 
centre, mm  At middle of beam  At ends of beam  
Siding, mm  Moulding, mm  Siding, mm  Moulding, mm  
4.2 505 50 75 50 50 
5.2 590 58 86.5   
NOTE  
1. The Table scantlings are based on a timber having a standard density of 560 kg/m3 and where timber of a different 
density is to be used the scantlings are to be modified in accordance with 5.1.4. 
2. Where the beam spacing differs from that given in the Table, the strength of the beam is to be modified in direct 
proportion.  
5.2.14.2.2  Where the coachroof deck is of plywood the thickness determined from Table 18 may be reduced 
by 30 % 
5.2.14.2.3  Where plywood is sheathed with a laid deck the combined thickness may be 30 % less than the 
thickness in Table 17 provided that: - 
(a) the combined density of th e plywood and sheathing is not less than 430 kg/m3 
(b) the thickness of the plywood is not less than 30 % of the combined thickness and in no case is 
less than 6 mm, and  
(c) where the laid planking is less than 19 mm, the seams are d with an approved flexible seam 
compound.  
5.2.14.2.4  If the coachroof deck is covered with canvas or other approved sheathing the thickness 
determined from Table 18 may be reduced by 1 .5 mm.  
5.2.14.2.5  Where the coachroof  beam spacing differs from that given in Table 18 the strength of the beams 
is to be modified in direct proportion and the deck thickness is to be modified at the rate of 1 .5 
mm per 50 mm difference.  
5.2.14.2.6  On small coachroofs where it is desired to dispense with  beams the deck thickness will be 
specially considered.  
5.2.14.2.7  The coachroof and side deck are to be adequately stiffened in way of the mast. Where a mast is 
stepped on the coachroof the structural arrangements will be specially considered.  
5.2.14.3  Deckhouses  
The scantli ngs of a deckhouse are dependent on the size of the house but the general standard of strength 
is to be that required for a coachroof and proposals will be specially considered.  
5.3 Scantlings for Hard Chine Vessels  
5.3.1  Keel and Hog  
5.3.1.1  The keel shall be sided and mou lded as indicated in Table 20, except in the case of single 
planked hard chine displacement vessels when they shall be as indicated in Table  3. The siding 
and moulding shown therein may be varied in accordance with the notes to these Tables.  
5.3.1.2  The minimum h og siding and moulding shall be as shown in Table 20 except in the case of single 
planked hard chine displacement vessels when they shall be as indicated in Table 3 but may be 
varied in accordance with the notes to these Tables.  
Table 20: Hard Chine vessels – Keel and Hog  
Hard Chine Vessels - Keel and Hog   
Keel Hog 
Measured  Section    
Section    
length  area Siding  Moulding  area Siding  Moulding  
m mm2 mm mm mm2 mm mm 
5 7350  70 105 4200  120 35 
6 8625  75 115 5400  135 40 
7 10625  85 125 6750  150 45 
8 12150  90 135 8250  165 50 
9 14250  95 150 9900  180 55 
10 16800  105 160 10 725  195 55  
©TBS 2023 -All rights reserved  50 Hard Chine Vessels - Keel and Hog   
Keel Hog 
Measured  Section    
Section    
length  area Siding  Moulding  area Siding  Moulding  
m mm2 mm mm mm2 mm mm 
11 18700  110 170 12600  210 60 
12 21600  120 180 14625  225 65 
13 23750  125 190 16800  240 70 
14 27000  135 200 19 125  255 75 
15 29400  140 210 20250  270 75 
16 33750  150 225 22800  285 80 
17 36425  155 235 25500  300 85 
18 40425  165 245 28800  320 90 
19 44200  170 260 31825  335 95 
20 48600  180 270 35000  350 100 
21 51800  185 280 36500  365 100 
22 56550  195 290 39900  380 105 
23 60000  200 300 43450  395 110 
24 65100  210 310 47150  410 115 
NOTES:  
1. Keel siding and moulding may be varied provided section area is maintained and siding is sufficient to provide 
0.25 times the table siding on each side of the shaft tube.  
2. Hog siding and moulding may be varied provided section area is maintained and  
(i). Siding is sufficient for garboard plank landings of at least 1.75 times prank thickness on either side of keel: 
and 
(ii). Moulding is sufficient to provide 2.5 times plank thickness.  
3. Vessels over 24 metres measur ed length will be specially considered by the Authority.  
5.3.1.3  The keel and hog may be either laminated or of solid timber construction. Where of solid timber 
construction the keel and hog in vessels less than 10 metres in length shall be in one length, 
and for vessels 10 metres in length and over where the keel or hog is not in one length it shall 
be efficiently scarphed.  
5.3.1.4  Where a keel or hog is scarphed, such scarphs shall be in accordance with 5.2.1 
5.3.2  Stem  
5.3.2.1  Stem scantlings at the heel shall in no case be less in siding and moulding than the scantlings 
for the keel determined from 5.3.1 and Table 20.  
5.3.2.2  The scarph of the stem to keel shall not be less than 2.5 times the keel moulding in length.  
5.3.3  Transom  
5.3.3.1  Transom th ickness shall be obtained from Table 21 and associated notes, except in the case of 
single planked hard chine displacement vessels when the transom thickness shall be obtained 
from Table 22  
5.3.3.2  Transom should have space to allow  for at least two outboard engi nes to be fitted for passengers 
and cargo vessels.  
Table 21: Hard Chine Vessels Transom  
Hard Chine Vessels - Transom  
  *Stiffeners  Margin  
Measured  Thickness      
length  plywood  Siding  Moulding  Siding  Moulding  
m mm mm mm mm mm 
5 12 50 25 75 35 
6 12 55 25 80 40 
7 12 60 25 85 45 
8 12 60 30 90 45  
51 ©TBS 2023 -All rights reserved  Hard Chine Vessels - Transom  
  *Stiffeners  Margin  
Measured  Thickness      
length  plywood  Siding  Moulding  Siding  Moulding  
m mm mm mm mm mm 
9 16 65 30 95 50 
10 16 70 30 100 50 
11 19 70 35 105 50 
12 19 75 40 110 55 
13 19 80 40 120 60 
14 24 85 45 125 60 
15 24 90 45 130 65 
16 24 95 45 140 65 
17 24 95 50 145 70 
18 24 100 50 150 75 
19 24 105 50 160 75 
20 24 110 55 165 80 
21 30 115 55 170 80 
22 30 115 60 180 85 
23 30 120 60 185 90 
24 30 125 65 190 90 
• Stiffeners spaced at 450mm centre to centre.  
NOTES:  
1. Where planking is used table thickness is to be increased by 25 %. 
2. Where stiffener spacing varies from the standard spacing of 450mm used in the table stiffener scantlings 
are to be adjusted by maintaining the section modulus of the stiffener per millimetre of stiffener 
spacing.  
3. Transom thickness may be decreased if the stiffener spacing is less than the basic 450mm as follows:  
(i). Plywood -3mm per 50mm  
(ii). Planking -3mm per 30mm.  
4. Plywood may be in multiple thicknesses to obtain the total thickness shown in the table.  
5. The table scantlings are for hardwood of 960 kg/m3 density and marine grade waterproof plywood.  
6. Vessels over 24 metres measured length will be specially considered by the Authority.  
Table 22: Transom  
Transom  
  *Stiffeners  Margin  
Measured       
length  Thickness  Siding  Moulding  Siding  Moulding  
m mm mm mm mm mm 
5 28 50 25 75 35 
6 30 55 25 80 40 
7 32 60 25 85 45 
8 34 60 30 90 45 
9 36 65 30 95 50 
10 38 70 30 100 50 
11 40 70 35 105 50 
12 42 75 40 110 55 
13 44 80 40 120 60 
14 46 85 45 125 60 
15 48 90 45 130 65 
16 50 95 45 140 65 
17 52 95 5O 145 70 
18 54 100 50 150 75  
©TBS 2023 -All rights reserved  52 Transom  
  *Stiffeners  Margin  
Measured       
length  Thickness  Siding  Moulding  Siding  Moulding  
m mm mm mm mm mm 
19 56 105 50 160 75 
20 58 110 55 165 80 
21 60 115 55 170 80 
22 62 115 60 180 85 
23 64 120 60 185 90 
24 66 125 65 190 90 
• Stiffeners spaced at 450 mm centre to centre.  
NOTES:  
1. Table thickness is for single thickness planked construction. Where diagonal or multiple skin construction is 
adopted, the thickness may be reduced to 0.75 of that in the table.  
2. Where stiffener spacing is less than the standard spacing or 450 mm used in the tabl e stiffener scantlings 
may be adjusted by maintaining the section modulus of stiffener per millimetre of stiffener spacing. For 
example:  
Vessel 20 m length -propose to use spacing -of 300 mm with siding of 100 mm:  
Modulus per millimetre at table scantlings and spacing = 123  
Required moulding = √123 ×300 ×6
100  = 47 mm  
3. Where the stiffener spacing is less than the basic 450 mm the transom thickness may be decreased for 
every decrease in the resulting space between the stiffeners at the rate of 3 mm per  30 mm decrease.  
5.3.3.3  Transoms shall have stiffeners, spaced at not more than 450 mm centres, together with margins. 
The stiffeners and margins shall have scantlings derived from Table 21 except in the case of 
single planked hard chine displacement vessels when  the scantlings shall be obtained from 
Table 22.  
5.3.3.4  A substantial knee shall be fitted and through bolted through the transom and the hog.  
5.3.4  Web Frames  
5.3.4.1  The scantlings for web frames are to be derived from Table 23. If the basic web frame spacing 
shown in Table 23 is not adopted, the scantling of the web frame shall be adjusted by maintaining 
the section modulus of the frame per millimetre of frame spacing.  
5.3.4.2  Where a web frame is notched in excess of 12.5 % of its depth to accommodate longitudinals, 
the moulding of the web frame shall be increased to maintain the required sectional area in way 
of the notch.  
5.3.4.3  A floor timber of siding equal to that of the web frame, is to be used to connect the web frame 
members across the top of the keel and hog  
5.3.4.4  Gussets or chocks shal l be used to connect the bilge and topside sections of web frames. These 
shall be of adequate scantling and through fastened by bolts. Where web frames are not in one-
piece  suitable strengthening shall be provided in way of any joint.  
5.3.4.5  Where web frames are used, intermediate frames of dimensions and spacings determined for 
bent frames are required to be fitted between the web frames.  
Table 23: Transverse web frames  
Transverse Web Frames  
Measured  Web frames  
length  *Spacing  Siding  Moulding  
m mm mm mm 
5 500 20 60 
6 550 25 65 
7 600 25 75 
8 650 30 80  
53 ©TBS 2023 -All rights reserved  Transverse Web Frames  
Measured  Web frames  
length  *Spacing  Siding  Moulding  
m mm mm mm 
9 700 30 90 
10 750 35 95 
11 800 35 105 
12 850 40 110 
13 900 45 120 
14 950 45 125 
15 1000  50 135 
16 1050  50 140 
17 1100  55 150 
18 1150  60 155 
19 1200  60 165 
20 1250  65 170 
21 1300  65 180 
22 1350  70 185 
23 1400  75 195 
24 1450  75 200 
• Spacing is measured from frame centre to frame centre.  
NOTES:  
1. Where the basic spacing shown in the table is not adopted, frame scantlings are to be adjusted by 
maintaining the section modulus of the frame per millimetre of frame spacing  
2. Frames of the above siding and moulding may be notched to a depth of not more th an 12.5 % of the moulding 
to house longitudinal stringers,  
5.3.5  Intermediate Frames in Longitudinally Planked Hard Chine Hulls  
Intermediate frames, of dimensions and spacing’s determined for the frames in round bilge hulls having the 
same measured length, are required to be provided and fitted between the web frames. These frames 
should be housed into the chine a distance of not m ore than 10mm for their full cross -sectional  area and 
dead nailed to the sheer clamp.  
5.3.6  Floors  
5.3.6.1  Floors shall be fitted at each transverse web frame and between web frames at not more than 
450 mm centres  
5.3.6.2  The siding and moulding of floors shall be determined fr om Table 24  
Table 24: Hard Chine Vessels Floor  
Hard Chine Vessels - Floor  
 *Floors  
 Measured 
length  Siding   Moulding at 
centre line  
m mm mm 
5 35 90 
6 35 100 
7 40 110 
8 40 120 
9 45 130 
10 50 140 
11 50 150 
12 55 160 
13 60 180 
14 60 190 
15 65 200  
©TBS 2023 -All rights reserved  54 Hard Chine Vessels - Floor  
 *Floors  
 Measured 
length  Siding   Moulding at 
centre line  
16 70 210 
17 70 220 
18 75 230 
19 80 250 
20 80 260 
21 85 270 
22 90 280 
23 90 290 
24 95 300 
* Floors spaced at 450mm centres.  
NOTES:  
1. Where floor spacing is less than 4 50mm, floor scantlings may be adjusted by maintaining  the section 
modulus of the floor at the vessel's centre line per millimetre of floor spacing  
2. Vessels over 24 metres measured length will be specially considered by the Authority.  
5.3.6.3  Where floors are fitted in the throat of a web frame then the si ding may be reduced to that of the 
web frame, provided the moulding is increased to maintain the section area at the vessel's 
centreline.  
5.3.6.4  Intermediate floors between web frames shall extend and be fastened to a stringer.  
5.3.7  Stringers  
5.3.7.1  The scantlings of bottom stringers shall be determined from Table 24 and associated notes.  
Table 25: Hard Chine vessels bottom stringers  
Bottom stringers  
Measured  
length  Spacing  Total section  area 
per side  Moulding  Siding  
m  mm  mm2 mm  mm  
5 215 2760  20 46 
6 245 4032  24 56 
7 270 5544  28 66 
8 295 7056  28 84 
9 260 8448  32 66 
10 280 9728  32 76 
11 300 11248  38 74 
12 320 12464  38 82 
13 280 14060  38 74 
14 300 15580  38 82 
15 325 17200  40 86 
16 345 18400  40 92 
17 310 20160  40 84 
18 330 21600  40 90 
19 340 22680  42 90 
20 355 24192  42 96 
21 325 25872  42 88 
22 340 27048  42 92 
23 355 28336  44 92 
24 370 30184  44 98 
NOTES:  
1. Where stringer spacing varies from the table, stringer scantlings are to be adjusted by maintaining the section  
55 ©TBS 2023 -All rights reserved  modulus of stringer per millimetre of stringer spacing  
2. Where the spacing of web frames supporting bottom or side stringers varies from the tabl e spacing the 
scantlings of stringers shall be increased or may be decreased for any increase or decrease respectively in 
web frame spacing by increasing or decreasing the section modulus in accordance with -the formula:  
Z1 = Z (𝑆12
𝑆2) 
Where Z = section mod ulus of table stringer as adjusted for stringer spacing, if applicable.  
Z1 = required section modulus at new. spacing  
S1 = table spacing for web frames  
S = new spacing for web frames  
3. Vessels over 24 metres  measured length will be specially considered by the Authority.  
5.3.7.2  A reduction in scantlings to 60 % of the scantlings determined from Table 25 may be made for 
side stringers.  
5.3.7.3  Stringers should run for the full length of the vessel wherever possible.  
5.3.7.4  Where practicable, stringers should be in one length. If not in one length stringers shall be 
scarphed.  
5.3.7.5  Where stringers are scarphed, scarphs shall be not less in length than 6 times the dimension of 
the edge or face scaphed, and suitably fastened.  
5.3.7.6  Feather edge scarphs shall be suitably fastened and glued.  
5.3.8  Chines  
5.3.8.1  The minimum scantlings for chines shall be determined from Table 26  
Table 26: Hard Chine vessels Chines  
Vessels Chines  
Measured  length  Sectional  area Siding  Moulding  
m  mm2  mm  mm  
5 1458  27 54 
6 1800  30 60 
7 2312  34 68 
8 2628  36 73 
9 3200  40 80 
10 3872  44 88 
11 4560  48 95 
12 5354  52 104 
13 6272  56 112 
14 6844  58 118 
15 7688  62 124 
16 8712  66 132 
17 9248  68 136 
18 10366  72 144 
19 10952  74 148 
20 12168  78 156 
21 12800  80 160 
22 13440  82 164 
23 14450  85 170 
24 15480  88 176 
5.3.8.2  The ratio of siding to moulding of chines is generally not to be greater than 1 to 2. In any case 
the siding shall be sufficient to provide a faying surface equal to 2.5 times the thickness of the 
bottom planking.  
5.3.8.3  Where practicable, chines should be in one length. If not in one length chines shall be scarphed.   
©TBS 2023 -All rights reserved  56 5.3.8.4  Where chines are scarphed, scarphs shall be not less in length than 6 times the siding and 
suitably fastened.  
5.3.8.5  The ends of diagonal planking and plywood shall be protected at the chine edge.  
5.3.9  Chines for Single Planked Vessels  
(a) The dimensions of chines are to be determined from Table 27  
(b) Where practicable, chines should be in one length, but may be scarphed, in which case the sca rphs 
shall be not less in length than 6 times the moulding and be edge bolted.  
Table 27: Chines and Stringers (Single planked hulls)  
Measured  
length  Chines  Stringers  
Section  
area siding  moulding  Section area  per 
side siding  Moulding  
m mm2 mm mm mm2 mm mm 
5 1950  30 65 5400  60 30 
6 2450  35 70 5850  65 30 
7 3000  40 75 7350  70 35 
8 3600  45 80 8400  80 35 
9 4250  50 85 9600  80 40 
10 4950  55 90 11400  95 40 
11 6000  60 100 14175  105 45 
12 7150  65 110 14850  110 45 
13 8050  70 115 18000  120 50 
14 9375  75 125 18750  125 50 
15 10800  80 135 22275  135 55 
16 12325  85 145 23100  140 55 
17 13950  90 155 27000  150 60 
18 15675  95 165 31200  160 65 
19 17000  100 170 32175  165 65 
20 18375  105 175 36750  175 70 
21 19800  110 180 37800  180 70 
22 21 275  115 185 42750  190 75 
23 22800  120 190 45000  200 75 
24 24375  125 195 49200  205 80 
NOTES:  
1. At least 3 stringers shall be fitted on each side of a round bilge hull and in the bottom of chine hulls. Where 
more than 3 stringers are fitted their scantlings shall be subject to special consideration by the Authority.  
2. Stringers may be laminated. Each lamination should be not less than 12mm in thickness  
3. Scantlings of chines and stringers may be reduced from those shown in the table by a uniform taper of both 
siding and moulding by up to 20 % of the cross -sectional area beyond 0.6L amidships.  
5.3.10  Beam Shelf/Sheer Clamp  
5.3.10.1  A suitable beam shelf and/or sheer clamp shall be fined and the minimum section area shown 
in Table 28 is to be maintained.  
Table 28: Hard Chine Vessels - Beam Shelf/ Sheer Clamp  
Measured length  Section area  
m  mm2  
5 2300  
6 2500  
7 3250  
8 4050  
9 4900  
10 6000  
11 6970  
12 7420   
57 ©TBS 2023 -All rights reserved  Measured length  Section area  
m  mm2  
13 8500  
14 9620  
15 10800  
16 12350  
17 13650  
18 15370  
19 15750  
20 17200  
21 19120  
22 20700  
23 22320  
24 24500  
NOTE:  
Vessels over 24 metres measured length will be specially considered by the Authority.  
5.3.10.2  The siding of the sheer clamp shall be sufficient to maintain faying surfaces equal to twice the 
deck planking thickness.  
5.3.11  Fitting of Longitudinal Members  
5.3.11.1  Beyond 0.6L amidships the scantlings of stringers, chines, sheer clamps and beam shelves 
may be reduced by a uniform taper of both moulding and siding by up to 20 % of the cross -
sectional  area shown in the Tables.  
5.3.11.2  Scarphs in stringers, sheer clamps, beam shelf etc. may not be closer than the web frame 
spacing, measured between the closest extremities of the scarphs considered.  Scarphs are 
not permitted in way of bulkheads, web frames or in line with keel scarphs. The scarph in a 
sheer clamp shall not be closer to the butt in a sheer strake than one web frame spacing.  
5.3.11.3  Breasthooks of grown timber or chocks of straight grain or brackets are to be fitted at the 
forward end of th e hull between the stem and: .  
(i) Sheer clamp  
(ii) Chines in vessels of 12.5 metres in length and over.  
5.3.11.4  Grown knees, solid chocks or brackets are required to be fitted between the transom and:  
(i) Sheer clamp  
(ii) Chines in vessels of 12.5 metres  in length and over  
(iii) Every second stringer in vessels of 12.5 metres in length and over.  
5.3.12  Watertight Bulkheads  
Watertight Bulkheads are to have scantlings determined from 3.2.8 and associated notes.  
5.3.13  Hull Planking  
5.3.13.1  The hull planking thickness shall be determin ed in accordance with Table 29 and associated 
notes.  
5.3.13.2  Where in double planked fully glued diagonal construction the planking layers are laid parallel 
to each other, then the overlap between alternate layers shall be not less than 4 times the plank 
thickness  and not more than half the plank width.  
Table 29: Hard Chine Vessels - Hull Planking Thickness  
Measured length  Bottom  Topside  
Plywood  Double diagonal  Plywood  Double diagonal  
m mm mm mm mm 
5 9 15 9 15 
6 11 17 9 15 
7 12 19 9 15 
8 14 21 11 16·  
©TBS 2023 -All rights reserved  58 Measured length  Bottom  Topside  
Plywood  Double diagonal  Plywood  Double diagonal  
m mm mm mm mm 
9 15 23 11 18 
10 16 25 12 19 
11 18 26 14 20 
12 20 28 15 21 
13 21 30 16 23 
14 22 32 17 24 
15 24 34 18 26 
16 25 36 19 27 
17 27 38 20 29 
18 28 40 21 30 
19 30 42 22 32 
20 31 44 23 33 
21 33 45 25 34 
22 34 47 26 36 
23 36 49 27 37 
24 37 51 28 39 
NOTES:  
1. Where stringer spacing differs from the basic stringer spacing’s shown in Table 25 planking thickness shall 
be increased and may be decreased for every increase or decrease respectively in the resulting span 
between stringers as follows:  
(i). Plywood -3 mm per 50 mm difference  
(ii). Diagonal planking -3 mm per 30 mm difference.  
2. Plywood may be in multiple thicknesses to obtain the total thickness shown in the table.  
3. The table scantlings are for hardwood of 960 kg/m3 density and marine grade water -proof plywood to 
Australian Standard AS 2272 -Plywood for Marine Craft.  
4. Table thicknesses for double diagonal planking are applicable only to hulls where planking layers are glued 
together.  
5. Vessels over 24metres measured length will be specially considered by the Authority.  
5.3.14  Deck Beams  
Scantlings of ordinary deck beams are not to be less than those determined from 5.2.10 and associated 
notes.  
5.3.15  Deck Planking  
Deck planking thickness shall be determined in accordance w ith 5.2.11 and associated notes.  
5.3.16  Pillars  
The scantlings of pillars shall be determined in accordance with 5.2.12 and associated notes.  
5.3.17  Engine Seating  
The installation of engine seating shall be in accordance with 5.2.13 and associated notes.  
5.3.18  Deckhouses  
Deckhouses are to have scantlings determined from 5.2.14 and associated notes.  
5.4 Supplementary Provisions  
5.4.1  Additional requirements for passenger boats  
Sufficient handrails shall be securely installed on the outside of wheelhouse, deckhouse and in the 
interior of  wheelhouse/deckhouse to the satisfaction of the Surveyor.  
5.4.2  Additional requirements for fishing boats  
5.4.2.1  In every decked vessel, sufficient bulwarks, guard rails or guard wires shall be provided at the 
exposed parts of the freeboard and superstructure decks and the tops of any deckhouses or 
companionways used in the operation of the vessel.  
5.4.2.2  In every decked vessel, adequate guard rails, lifelines, gangways or passages shall be provided  
59 ©TBS 2023 -All rights reserved  for the passage of the crew between their quarters, ma chinery spaces and working spaces. 
Storm rails shall be fitted on the outside of all deckhouses and casings.  
5.4.2.3  Controls of winches, line and net hauling shall be placed in a manner that the operators have 
ample room for their unimpeded operation and that the y have a clear view on the working area. 
The winches and equipment shall be fitted with safety devices that are designed to prevent 
accidents.  
5.4.2.4  Flooring in fish rooms may be of either cement or timber. Where of cement, drain channels are 
to be fitted, drain ing to the bilge or slushwell.  
5.4.2.5  All grounds and hull structure not easily accessible after completion of construction are to be 
treated with at least three coats of a non -toxic wood preservative.  
6 Manufacturing Facilities and Workmanship  
6.1 Manufacturing  Facil ities 
6.1.1  Workshop conditions, material storage, and handling must be such that materials shall be free from 
contamination, readily accessible, and appropriate for the vessel to be built.  
6.1.2  Materials that would deteriorate with exposure to the weather shall be s tored under cover.  
6.1.3  The Boatbuilder shall have processes to effectively monitor, verify and document the quality of 
construction and compliance with design documentation throughout the build program and at its 
completion.  
NOTES:  
1. This would include ongoing i nspections and/or tests at critical stages of construction.  
2. A quality management system provides a widely recognized  framework to facilitate the compliance of a 
vessel with quality and compliance standards.  
6.1.4  All boatbuilding manufacturing  facilities shall be identified, recognized and registered by  the 
overseeing authority . 
6.2 Workmanship  
6.2.1  General  
The workmanship applied to the construction of vessels shall be of sufficient quality to achieve the 
outcomes of structural strength and watertight integrity required by the provisions of this standard.  
All boatyard workers shall be registered by  the overseeing authority  with identification numbers that 
categorise areas of specialization and expertism.  
6.2.2  Construction procedure  
6.2.2.1  Workshop requirements  
All boatyard workshops shall be inspected by surveyor(s) and on successful inspection, workshop safety 
certificate shall be iss ued.  
The craft is to be suitably protected during the building period from adverse weather and climatic 
conditions. The minimum protection to be provided is normally a substantial and efficient roof projecting 
beyond the length and breadth of the craft. W here laminated glued construction is being extensively 
used, a building shed with controlled temperature and humidity levels may be required.  
6.2.2.2  Workmanship is to be well executed and carried out under adequate supervision throughout the 
preparation and build ing of the craft. The various parts of the structure are to be properly faired 
and fitted.  
6.2.2.3  When a hull is to be transported for fitting out and completion elsewhere, the construction should 
be progressed to a stage commensurate with the method of transport  to be used.  When a 
partially completed vessel is to be towed or propelled afloat, the Boatbuilders are to ensure that 
its stability and  weathertightness is adequate prior to its removal from the Boatbuilders yard.  
6.2.3  Preservative treatment  
The preservatives  are preferably to be applied by dipping and soaking or by pneumatic spray but where 
these methods are not practicable a liberal application by brush can be used. The timber is to be treated 
when all work on the member is complete, but where cut or bored a fter treatment a liberal brush 
application is to be applied to the exposed timber.   
©TBS 2023 -All rights reserved  60 6.2.4  Plywood  
All edges and cut -out areas are to be thoroughly sealed by glues, varnishes, paints or other suitable 
compositions to prevent moisture penetrating along the end -grain. 
6.2.5  Gluing process  
6.2.5.1  The timber is to be clean and dry, and the joining surfaces are to be properly prepared and free 
from dust and grease. The adhesive is to be evenly applied and the joint closed within the 
manufacturer's recommended closing time in order to obtain a thin and uniform glue line. 
Sufficient clamps and other pressure devices are to be used and the pressure is not to be 
released until the joint has set.  
6.2.5.2  Modified urea -formaldehydes may be used in parts of the structure which will not be co mmonly 
subjected to continuously wet conditions and will be well ventilated. These parts include the 
coach roof and superstructures in both wood and plywood craft and internal structural 
assemblies which are clear of the bilges in plywood craft only. The g lue lines in these structures 
are to be protected by several applications of varnish or paint.  
6.2.5.3  The glues are to be mixed and applied in accordance with the manufacturer's instructions and 
with due regard to the shop temperature and humidity requirements. D ue attention is to be paid 
to the application techniques for the species of timber being glued and the manufacturer's advice 
should be sought in the working of difficult timbers and the effect of preservatives on the 
materials.  
6.2.6  Laminated timbers  
6.2.6.1  The layers  forming the lamination are generally to be of the same timber species and are to be 
of even moisture content. The grain of the layers is to be approximately parallel to the length of 
the member, and special attention is to be paid to grain in the selectio n and assembly of the 
timber.  
6.2.6.2  Where practicable the layers are to be continuous, and if this is not possible, the layers are to 
be scarph jointed, the slope of the scarph being not greater than 1 in 10.  
6.2.6.3  Where the layers are bent to produce members of curve d form, the thickness of each layer is to 
be such that the layer will not be unduly stressed in forming, and that a satisfactory inter laminar 
bond can be achieved.  
6.2.7  Fastening practice  
6.2.7.1  Attention is to be paid to the fastenings throughout, particularly the s ize and disposition. The 
boring of the timber to receive the fastenings is to be properly executed, according to the density 
of the timber and the type and material of the fastening.  
6.2.7.2  All hull and deck through -fastenings are to be of a composition similar t o that of any metal 
members they secure. Where this cannot be arranged, suitable insulation is to be fitted to prevent 
contact between dissimilar metals.  
6.2.7.3  Where craft are sheathed with copper or other non -ferrous metals, iron or steel fastenings are 
not to be used in way.  
6.2.7.4  Through bolts are to be clenched on rings or washers or are to be fitted with nuts. Nuts, rings or 
washers are to be of the same material as the bolts.  
6.2.7.5  Where bolt fastenings pass through the outside planking or centreline structure, cotton or other 
suitable grommets are to be fitted under the heads. Keel bolt and centreline fastening holes are 
to be treated with a suitable composition.  
6.2.7.6  Where screw fastenings are used, the thread of the screw must enter the frame or beam a 
minimum distance eq ual to the thickness of the hull or deck planking.  
7 Compliance and Boats Identification  
7.1 General  
It is the responsibility of the Boatbuilder/Owner of the new vessel to be constructed to this guideline  to 
inform the  Overseeing Authority  on the intention to b uild and register the vessel.  
7.1.1  Prior to commencement of construction the Boatbuilder/Owner is to provide the following information:  
61 ©TBS 2023 -All rights reserved  - 
(a) Dimensions and power;  
(b) Intended use of the vessel  
(c) Construction material with attached certificate of material assessment by a competent forest 
authority;  
(d) Place of build (hull)  
(e) Place of outfit (where differing from build location)  
(f) Proposed date of commencement of construction  
(g) Proposed date of completion of vessel  
(h) Area of operation  
(i) Boatyard certificate issued by  the Overseeing Authority   
7.2 Safety Compliance Notice  
7.2.1  Every Boat constructed according to these Guidelines  shall have fitted to it, in a conspicuous position, 
plainly visible from the helm (unless exempt by regulation), a Safety Compliance Notice issued by the 
Overseeing Authority  
A Compliance Notice is defined as either:  
(a) Conformity Label,  
(b) Capacity Label,   
Example of Marked Information  
The Conformity Label shall include the following:  
(a)  name of manufacturer;  
(b)  manufacturers  or constructor’s identification cod e, MIC;  
(c)  model type or number, or both;  
(d)  label number; and  
(e)  statement of compliance.  
Tanzania Shipping Agencies Corporation (TASAC)  
BOATBUILDER: ABC IMAGINARY CO (AAAA) ie MIC  
The manufacturer certifies that this Boat complies with the requirement of the construction Standards 
for wooden Boats  
MAXIMUM LOAD  MAXIMUM OCCUPANTS  MAXIMUM POWER  
--------------  kg  ---------------------------  Persons  ----------------- KW (HP)  
No._ XXXX0016  
Figure 21: Conformity Label Example  
7.3 Hull Identification Number (HIN)  
The identification code consists of 12 consecutive characters displayed as capital letters of the alphabet 
or Arabic numerals with no spaces, slashes (oblique’s), or hyphens between them. The code c omprises:  
(a) a three -digit Manufacturer’s Identification Code (MIC); followed by  
(b) a five-character  Manufacturer’s Hull Serial Number; and  
(c) four figures giving the date of manufacture.  
7.3.1  Manufacturer’s Identification Code (MIC)  
The MIC consists of three character s displayed as block capitals or numbers, forming the first three 
characters of the HIN, as issued by  the Overseeing Authority . 
7.3.2  Manufacturer’s Hull Number  
7.3.2.1  The fourth through eighth characters of the HIN are the individual Manufacturer’s Hull Number, 
which  is defined by the manufacturer.  
7.3.2.2  No two Boats shall be assigned the same Manufacturer’s Hull Number.  
7.3.2.3  The Manufacturer’s Hull Number shall consist of capital letters of the alphabet or Arabic 
numerals, or both, except that the letters “I,” “O,” and “Q” shall not be used.  
7.3.3  Date of Manufacture   
©TBS 2023 -All rights reserved  62 7.3.3.1  The ninth through twelfth characters of the HIN indicate the date of manufacture. The ninth 
character is a capital letter of the alphabet indicating the month from when the craft is considered 
to have commenced const ruction and is defined as follows:  
A=January, B=February, C=March, D=April, E=May, F=June, G=July, H=August, I=September, 
J=October, K=November, L=December  
7.3.3.2  The tenth is an Arabic numeral designating the last digit of the year of manufacture.  
7.3.3.3  Characters ele ven and twelve are Arabic numerals marking the model year of the Boat.  
ABC2AB41G091  
Manufacturer’s 
Identification Code (MIC)  Manufacturer’s Hull 
Number  Commencement of 
Construction  Model year  
ABC 2AB41  G0 91 
Figure 22: Example of Twelve -Digit Hull Identification Number (HIN)  
Figure 22 is a typical example of a complete twelve -digit HIN for a Boat where construction commenced 
in July 1990 for the 1991 model year  
  
63 ©TBS 2023 -All rights reserved  Annex A  
(informative)  
Mean Strength Properties of Tanzania Timbers  
SN. Botanical name  Trade name  Density  Static bending Centre 
loading  Compression  Hard 
(Resistance 
to 
indentation)  Shear   
 
At 12% m.c. 
Air  dried  Max 
bending 
strength  Stiffness  
Max. 
compression 
strength 
parrallel to 
grain  
On side grain  
Max. Shear 
strength 
parrallel to 
grain  
MOR  MOE  
   Kg/ m3 N/mm2 N/mm2 N/mm2 N N/mm2 
 1 2 3 4 5 6 7 8 
1.  Acacia mearnsii  Black wattle  722 121 14372  60.8 7778  15.6 
2.  Acacia melanoxvlon  Australian black wood  689 101 15269  60.44  4640  19.2 
3.  Acacia nigrescens  Mkambala  1122  132 13793  76.2 19067  21.8 
4.  Afzelia quanzensis  E.A. afzelia  833 114 10441  69.2 8222  19.0 
5.  Albizia amara  Mkengehovu  677 114.7  9753  50.8 - 20.5 
6.  Albizia gummifera  Mfuranji  465 79 8379  42.2 2844  15.3 
7.  Albizia versicolor  Mtanga  657 60 7227  43.0 4627  14.7 
8.  Albizia zygia  Nongo  577 89 10570  44.1 5155  15.4 
9.  Allanblackia stuhlmannii  Allanblackia (msambu)  - 76 19359  39.9 3849  10,2 
10.  Brachystegia spiciformis  Mtundu  817 (G)  126 13406  68.7 8133  18.0 
11.  Brachystegia microphylla  Mseni  769 93 9797  68.7 84444  19.1 
12.  Breonadia salicina  Mgwina  962 85 12504  61.6 9778  14.6 
13.  Callitris robusta  Cypress pine  561 78 6639  45.2 4400  - 
14.  Casearia battiscombei  White matua  625 85 9683  47.5 3209  14.3 
15.  Cassipourea malosana  Pillar wood  737 (G)  112 11602  67.7 5555  19.0 
16.  Cedrela odorata  Central American cedar  433 58 7538  36.0 2027  9.5 
17.  Cephalosphaera usambarensis  Mtambara  561 98 15791  46.2 3289  15.4 
18.  Chrysophyllum albidum  Mululu  721 133 13148  71.4 6933  - 
19.  Cinnamomum camphora 29 yrs  Japanese camphor  493 (G)  71 7814  38.8 2875  12.0 
20.  Cocoa nucifera  Mnazi  601 67 77938  45.4 4813  8.1 
21.  Cordyla africana  Mroma  833 84 11248  59.8 7022  - 
22.  Croton megalocarpus  Musine  705 102 - 53.9 6000  - 
23.  Cupressus lusitanica (18yrs)  E.A. cypress  481 73 8172  42.3 2698  14.2 
24.  Diospyros abyssinica  Msambu       17.3 
25.  Diospyros mespiliformis  African ebony  753 98 11145  53.0 6769  18.6 
26.  Ekebergia capensis  Ol mokuma  497 58 - 28.7 4000  -  
©TBS 2023 -All rights reserved  64 SN. Botanical name  Trade name  Density  Static bending Centre 
loading  Compression  Hard 
(Resistance 
to 
indentation)  Shear   
 
At 12% m.c. 
Air  dried  Max 
bending 
strength  Stiffness  
Max. 
compression 
strength 
parrallel to 
grain  
On side grain  
Max. Shear 
strength 
parrallel to 
grain  
MOR  MOE  
   Kg/ m3 N/mm2 N/mm2 N/mm2 N N/mm2 
 1 2 3 4 5 6 7 8 
27.  Entandrophragma exceisum  Mrie 465 52 7154  33.7 2044  10.9 
28.  Erithrophieum africanum  Mkarati  - 162 15404  97.1 12978  26.4 
29.  Erithrophieum suaveolens  Mwavi  978 145 14180  91.7 8222  16.6 
30.  Eucalyptus botryoides (20 yrs)  Southern mahogany  779 124 14676  66.0 5693  16.9 
31.  Eucalyptus globulus (14 yrs)  Tasmanian blue gum  784 108 14041  62.6 5867  17.2 
32.  Eucalyptus globulus (19 yrs)  Tasmanian blue gum  662 97 11572  49.7 3435  13.8 
33.  Eucalyptus maideni (14yrs)  Maiden’s gum  807 131 16000  66.7 7164  18.3 
34.  Eucalyptus maideni (20 yrs)  Maiden’s gum  843 121 12558  60.7 6253  17.0 
35.  Eucalyptus microcorys (15yrs)  Tallow -wood  849 117 14055  66.9 5867  19.6 
36.  Eucalyptus paniculata (14 yrs)  Paniculata gum  626 88 10283  51.6 3747  13.6 
37.  Eucalyptus paniculata (47 yrs)  Paniculata gum  1010  182 24879  96.3 13778  20.2 
38.  Eucalyptus regnans (14 yrs)  Australian ash  570 75 9600  45.4 3373  14.4 
39.  Eucalyptus salgina (35 yrs)  Blue gum  753 123 16887  67.6 6133  12.2 
40.  Eucalyptus saligna (14 yrs)  Blue gum 527 81 9924  44.9 2533  11.6 
41.  Fagaropsis angolensis  Mafu  673 110 13565  61.7 6080  19.6 
42.  Ficalhoa laurifoloia  Mkuka  675 94 10634  52.5 4978  13.4 
43.  Grevillea robusta  Grevillea  609 62 7154  36.3 3733  8.8 
44.  Hagenia abyssinica  Ol kijabe  657 90 9138  50.4 5218  18.4 
45.  Hallea rubrostipulata  Mromberombe  625 84 10055  47.6 3689  12.8 
46.  Hymenaea verrucosa  Mtandarus  817 111 11227  61.4 9244  22.9 
47.  Ilex mitis  Msaira  597 66 7890  35.3 5107  12.5 
48.  Isoberlinia scheffieri  Mbarika  801 108 13676  58.8 6293  13.3 
49.  Julbernardia globiflora  Muwa  946 142 14566  81.1 12267  23.8 
50.  Juniperus procera  African pencil cedar  513 91 8379  39.3 1911  12.8 
51.  Khaya anthotheca  Mkangazi  657 66 9604  48.3 5111  10.1 
52.  Macaranga conglomerata  Muhaa  465 62 8014  36.9 2267  11.7 
53.  Macaranga kilimandscharica  Muhaa  497 71 - 43.1 3111  - 
54.  Manilkara obovata  Nkunya  1026  158 19143  82.0 15244  19.7 
55.  Maranthes goetzeniana  Nganga  929 101 11988  52.8 8444  15.0 
56.  Markhamia platycalyx  Msambia  561 110 - 56.3 - -  
65 ©TBS 2023 -All rights reserved  SN. Botanical name  Trade name  Density  Static bending Centre 
loading  Compression  Hard 
(Resistance 
to 
indentation)  Shear   
 
At 12% m.c. 
Air  dried  Max 
bending 
strength  Stiffness  
Max. 
compression 
strength 
parrallel to 
grain  
On side grain  
Max. Shear 
strength 
parrallel to 
grain  
MOR  MOE  
   Kg/ m3 N/mm2 N/mm2 N/mm2 N N/mm2 
 1 2 3 4 5 6 7 8 
57.  Pseudolachnostylis maprouneifolia  Mtunguru  876 106 12400  54.4 7809  17.6 
58.  Milicia excelsa  Mvule  657 90 9345  54.7 5600  15.6 
59.  Millettia stuhlmannii  Pangapanga  849 118 12697  71.5 7227  20.2 
60.  Neoboutonia macrocalyx  Mfurufuru  390 50 8034  27.4 1662  9.1 
61.  Newtonia buchananii  Mkufi  561 97 9926  50.1 4622  15.4 
62.  Newtonia paucijuga  Mdadalike  721 98 11393  56.5 6120  19.5 
63.  Ocotea usambarensis  E.A. camphor  593 91 9926  52.5 4133  16.5 
64.  Ocotea usambarensis (second growth 40 yrs)  E.A. camphor wood  529 79 9281  48.8 2844  13.4 
65.  Olea capensis  Loliondo  737 91 10828  59.2 6267  18.9 
66.  O. capensis var. macrocarpa  Musharagi  913 174 17467  84.0 12178  28.1 
67.  Parinari exelsa  Mula  753 123 13406  65.8 7644  20.1 
68.  Pericopsis angolensis  E.A. percopsis  946 111 12317  76.0 10018  20.1 
69.  Pinus caribaea (13yrs)  Caribbean pine  421 51 6076  31.9 1760  9.2 
70.  Pinus montezumae (18yrs)  Mexican pine  447 58 7896  33.2 2204  11.6 
71.  Pinus patula (17yrs)  Patula pine  417 61 6445  34.5 1467  11.2 
72.  Pinus patula (22yrs)  Patula pine  449 71 7605  39.5 1867  12.9 
73.  Pinus patula (30yrs)  Patula pine  - 83 9023  46.7 2578  14.6 
74.  Pinus patula (15yrs)  Patula pine  505 56 8228  31.6 2044  8.8 
75.  Pinus patula (25yrs)  Patula pine  518 52 8317  33.2 2342  10.3 
76.  Pinus radiata (18yrs)  Radiata pine  465 51 7759  33.7 2138  10.7 
77.  Pinus radiata (33yrs)  Radiata pine  611 87 11945  52.4 - - 
78.  Podocarpus spp  Podo  513 82 8057  43.1 3689  15.1 
79.  Polyscias fulva  Mfumbati  368 38 5834  26.2 1196  8.0 
80.  Populus canescens  Grey poplar  616 75 9663  45.9 3209  13.3 
81.  Pouteria adolfi -friedericii  Manu  535 63 7331  25.8 2933  12.7 
82.  Pseudolachnostylis maprouneifolia  Mtunguru  876 106 12400  54.4 7809  17.6 
83.  Pterocarpus angolensis  Muninga  657 94 8443  57.0 6578  17.2 
84.  Pterocarpus tinctorius  Muninga maji  765 88 9842  58.1 8500  17.9 
85.  Prunus  Mueri  785 122 11279  63.2 8267  19.9 
86.  Sclerocarya birrea  Mng’ong’o  561 53 3931  35.2 4222  14.2  
©TBS 2023 -All rights reserved  66 SN. Botanical name  Trade name  Density  Static bending Centre 
loading  Compression  Hard 
(Resistance 
to 
indentation)  Shear   
 
At 12% m.c. 
Air  dried  Max 
bending 
strength  Stiffness  
Max. 
compression 
strength 
parrallel to 
grain  
On side grain  
Max. Shear 
strength 
parrallel to 
grain  
MOR  MOE  
   Kg/ m3 N/mm2 N/mm2 N/mm2 N N/mm2 
 1 2 3 4 5 6 7 8 
87.  Sclerocarya caffra  Mng’ong’o  545 51 5607  29.3 3689  11.0 
88.  Spirostachyys africana  Msaraka  962 107 8637  59.9 8933  19.6 
89.  Sterculia appendiculata  Mgude  430 67 9098  40.0 -- 10,3 
90.  Sterculia quinqueloba  Mbalamwezi  753 75 9539  41.5 5955  11.5 
91.  Strombosia scheffieri  Msangana  881 123 14159  68.4 7507  - 
92.  Bobgunnia madagascariensis  Kasanda  1080  158 18700  81.3 - 18.7 
93.  Tectona grandis (20yrs)  Teak  625 85 10930  52.5 3969  15.0 
94.  Terminalia ivorensis  Idigbo  540 79 10686  46.0 - 11.8 
95.  Terminalia sambesiaca  Mkurungu  753 98 11903  62.1 6351  18.3 
96.  Terminalia superba  Afara  383 32 5103  25.5 1369  7.6 
97.  Vitex doniana  Mfuru  481 43 4676  28.0 3044  8.9 
98.  Warburgia stuhlmannii  E.A. greenheart  873 111 11703  61.9 8169  19.7 
99.  Xeroderris stuhlmannii  Xeroderris  817 114 14200  62.0 - 15.0 
100.  Xymalos monospora  Mburano  577 74 8731  45.6 3542  15.0 
101.  Zanha africana  Mkalya  801 80 8731  48.3 6689  17.1 
Source: The commercial Timbers of Tanzania by J.M. Bryce and Revised by A.W.  Chihongo.  
 Third edition 2003, published by Tanzania Forestry Research Institute.   
67 ©TBS 2023 -All rights reserved  Annex B  
(informative)  
Swahili Terms in Wooden Boat Building  
SN English Name  Swahili Name  
1.  A beam  Tanga kati   
2.  Abaft  Tezi  
3.  Aboard  Chomboni  
4.  Amidships  omo 
5.  Aperture  Kidirisha  
6.  Armature  Amecha  
7.  Ballast  Farumi, weka Farumi au changarawe  
8.  Bilge Stringer  Tamkisi  
9.  Boom  Foromali  
10.  Bulk Head  Ukuta wa ndani/kiambaza  
11.  Bulwark  Kinga  
12.  Clamp  Darumeti  
13.  Clinker  Mavi chuma  
14.  Clinker Bilt  Jengo mweleko  
15.  Corrosion  Mbabuo anga hewa  
16.  Covering Board  Flali 
17.  Deck  Staha  
18.  Deck Beam  Fundo  
19.  Engine Bed  kitanda cha injini  
20.  Engine Bed Bolts  Bolti za kitanda  cha injini  
21.  Engine Box  Sanduku la injini  
22.  Engine Floor  Sakafu ya injini  
23.  Fender  Kofi 
24.  Floor Beams  Mbao za kufungia mlingoti  
25.  Floor Boards  Mbao za sakafu  
26.  Floors  Aligama  
27.  Foundation Bolts  Misumari ya ghabu  
28.  Frame  Taluma  
29.  Free hand sketch  Mkakato  
30.  Garboard  Mbao za matiki  
31.  Hatch  Falika  
32.  Hog/Keelson  Bitana  
33.  Keel Mtako/Mkuku  
34.  Keel Bolts  Misumari yam kuku  
35.  Keel Scarph  Skafu ya Mkuku/Mtako  
36.  Knee  Betana  
37.  Longitudinal Beam  Darumet  
38.  Mast  Mlingoti  
39.  Mast Partner  Kifundo  
40.  Mast Step  Mastem  
41.  Outrigger Boom  Mkingiko  
42.  Outrigger Clamp  Kiwango  
43.  Planking  Mbao za mbavuni  
44.  Plug Hasho  
45.  Railing  Mahilenyi  
46.  Rudder  Usukani  
47.  Samson Post  Mangili  
48.  Seam  Jongo   
©TBS 2023 -All rights reserved  
 68 SN English Name  Swahili Name  
49.  Seat or After Deck  Staha  
50.  Sheer Clamp  Kofi 
51.  Stem  Fashini ya mbele  
52.  Stem Knee  Betana ya mbele  
53.  Stern  Shetri  
54.  Stern Knee  Betana ya nyuma  
55.  Stern Post  Fashini ya nyuma  
56.  Stiffener  Kiyabisishi  
57.  Stop Water  Gurunzi  
58.  Thwart  Kiti 
59.  Tiller  Kana  
60.  Transom  Chanda  
61.  Transom Knee  Betana ya chanda  
62.  Ventilation Hole  Tundu la hewa  
63.  Vessel/Craft  Chombo  
64.  Water Proof  Jarabati maji  
65.  Worm Shoe/Keel shoe  Kiatu cha mkuku   
69 ©TBS 2023 -All rights reserved  Annex C  
(infor mative)  
Sample scantling for round bilge hull  
Main dimensions: Loa= 20m, Breath = 6.2m and Depth = 2.4m  
Table   C.1: Keel, hog, stem, stern post and fastenings for motor, sailing and auxiliary craft  
Length,  
L, m Moulding and siding of keel  Siding and 
moulding of stem 
at heel, mm  Siding and 
moulding of stem 
at head and 
sternpost mm  Diameter of bolts, 
mm, Sailing and auxiliary  Motor  
Moulding.  
mm Siding,  
mm Minimum 
siding of 
keel, mm  
 Sectional 
area of 
keel or 
keel and 
hog, cm2 Sailing 
and 
auxiliary  Motor  Sailing 
and 
auxiliary  Motor  Centreline 
structure  Keel 
scarph  
20 195 385 150 520 205 195 165 150 20 14 
See associated notes  
Table   C.2: Frames for Motor , Sailing and Auxiliary Craft  
Depth, D, m  Type 2 Grown frame only  Motor  
Sailing  and 
auxiliary  
Siding, mm  Moulding, mm  
Frame 
Spacing,  
, mm  At heel  
At head  
- 2.4 42 50 37 255 
2.4 - 52 61 46 280 
Table   C.3: Floors for motor, sailing and auxiliary craft  
Depth, D. m  Floors on grown or laminated frames  
Motor  Sailing 
and 
auxiliary  Length of arms.  
mm Strap floors.  
mm Wood floors at middle line  
Steel angle 
bar mm  For 3/5L 
amid -ship Beyond 3/5L 
amid -ship At throat  At point  Moulding mm  Siding 
mm 
- 2.4 480 350 45 x 16  40 x10  95 45 45 x.45 x5  
2.4 - 530 390 50 x 19  45 x 10  115 55 50 x.50 x5  
See associated notes  
Table   C.4: Floor fastenings for motor, sailing and auxiliary craft   
©TBS 2023 -All rights reserved   70 Depth, D, mm  Diameter of bolts in  throat, mm  Diameter of bolts at arms, mm  
Motor  Sailing and 
auxiliary  Grown 
laminated or 
steel frame  Bent frame  Grown 
laminated or 
steel frame  Bent frame  
- 2.4 12 8 8 6 
2.4 - 12 10 10 8 
See associated notes  
Table   C.5: Beam shelf and bilge stringer scantlings and fastenings for motor, sailing and auxiliary craft  
Length
, L, m Cross -sectional 
area of beam -shelf, 
cm2 Cross -sectional 
area of bilge 
stringer, cm2 Diameter of bolts, mm,  Steel side 
keelson and 
bilge stringer 
angles, mm  
Sailing 
and 
auxiliary  Motor  Sailing 
and 
auxiliary  Motor  Arms of 
breast -
hook  Beam 
shelf 
stringers  Hanging 
knees   
20 150 130 105 100 14 12 12 75 x65 x 5.5  
NOTE  
The Table scantlings for the beams shelf and bilge stringer are based on a timber having a standard density of 560 kg/m3 and where timber of a different density is 
to be used the scantlings are to be modified in accordance with 5.1.4. 
Table   C.6: Timber bulkheads  
Height of 
bulkhead  Planking  Stiffener  
Double 
planked  Ply- 
wood  Stiffener 
spacing  Moulding  Siding  
m mm mm mm mm mm 
2.5 50 25 450 115 65 
See associated notes  
Table   C.7: Bulkhead plating and stiffeners for motor, sailing and auxiliary craft  
Bulkhead plating and spacing of stiffeners  Stiffeners with free ends  
Depth of  bulkhead at  
middle line  Thickness of plating, 
mm Spacing of stiffener, 
mm Overall length of 
stiffener, m  Height of upper deck above top of 
stiffener, m  
0 0.6 1.2 1.8 2.4 
Modulus, cm3 
2.4 4.0 375 2.4 13.0 20.0 26.0 33.0 39.0 
See associated notes   
71 ©TBS 2023 -All rights reserved  Table   C.8: Outside and deck planking for motor. Sailing and auxiliary craft  
Length, L, m  Basic thickness, mm  
20 41.5 
See associated notes  
Table   C.9: Fastenings for outside end deck planking in motor, sailing end auxiliary craft  
Planking 
thickness, 
mm Size of fastenings  Number of fastenings per plank  
Outside planking  Deck planking  Width of plank  
Grown, laminated or steel frames  Bent frames  
Wood screws 
diameter  Bolt, 
mm Under 
100 
mm 100 mm 
and 
under 
150mm  150 mm 
and 
under 
180mm  180 mm 
and 
under 
205mm  205mm 
and under 
225mm  
Bolt, 
mm Wood screws 
diameter  Cooper bolt 
nails*size  Cooper bolt 
nails size   
mm gauge  mm gauge  mm gauge  mm gauge    
41.5 10 8 18 9.5 3.0 6 4 7 16 8 1 2 2 2 3 
See associated notes  
Table   C.10: Beams and hanging knees for motor, sailing and auxiliary craft  
Lengt
h of 
beam
, m Spacin
g of 
ordina
ry 
beams 
centre 
to 
centre, 
mm Ordinary beams 3/5L amidship  Ordinary beams beyond 3/5L 
amidship, half beam throughout  Beams in way of masts and at ends 
of deck openings  Strap hanging knees to deck beams  
At middle  At ends  At middle  At ends  At middle  At ends   Length of arm, 
mm At 
throa
t, 
mm At 
point
, mm  Sidin
g, 
mm Mouldin
g, mm  Sidin
g, 
mm Mouldin
g, mm  Sidin
g, 
mm Mouldin
g, mm  Sidin
g, 
mm Mouldin
g, mm  Sidin
g, 
mm Mouldin
g, mm  Sidin
g, 
mm Mouldin
g, mm  Numb
er on 
each 
side For 
3/5L 
amidsh
ip Beyond 
3/5L 
amidsh
ip 
6.3 625 88 125 88 88 70 100 70 70 112 156 112 112 11 675 540 70x3
3 54x1
4 
See associated notes  
Table   C.11: Longitudinal steel items for motor. sailing and auxiliary craft  
Length, m  Upper deck 
sheerstrake and 
stringer plate 
3/5L amidship, 
mm Upper deck 
sheerstrake and 
stringer plate at  
ends and cabin  
deck stringer 
plate, mm  Upper deck tie 
plates, mm  Upper deck 
stringer  angle, 
mm cabin deck tie 
plates, mm  cabin deck 
stringer angle, 
mm 
20 410 x4,5  280 x4  140 x4.5  50 x50 x 5  90 x4  55 x55 x4   
©TBS 2023 -All rights reserved   72 Table   C.12: Steel angle beams at upper and cabin decks for motor, sailing and auxiliary craft  
Length 
of beam, 
m Spacing 
of beams, 
mm Upper deck beams, mm  Upper deck beams, mm  
Without pillars  Thickness of 
knee  With one row of 
pillars  Thickn
ess of 
knee  Without pillars  Thickn
ess of 
knee  With one row 
of pillars  Thickne
ss of 
knee  
6.3 545 140 x 75 x12  7.5 90 x 75 x6.5  6.5 135 x75 x7 .5 7 75 x65 x6  6  
73 ©TBS 2023 -All rights reserved  Annex D  
(informative ) 
Sample scantling for hard chine hull  
Main dimensions: Loa= 20m, Breath = 6 .2m and Depth = 2.4m  
Table   D.1: Hard Chine vessels – Keel and Hog  
 Keel Hog 
Measured  Section    Section    
length  area Siding  Moulding  area Siding  Moulding  
m mm2 mm mm mm2 mm mm 
20 48600  180 270 35000  350 100 
Table   D.2: Hard Chine Vessels Transom  
  *Stiffeners  Margin  
Measured  Thickness      
length  plywood   Moulding  Siding  Moulding  
m mm mm mm mm mm 
20 24 110 55 165 80 
Table   D.3: Transom  
  *Stiffeners  Margin  
Measured       
length  Thickness  Siding  Moulding  Siding  Moulding  
m mm mm mm mm mm 
20 58 110 55 165 80 
Table   D.4: Transverse web frames  
Transverse Web Frames  
Measured  Web frames  
length  *Spacing  Siding  Moulding  
m mm mm mm 
20 1250  65 170 
Table   D.5: Hard Chine Vessels Floor  
 *Floors  
Measured  Moulding at  
length  Siding  centre line  
m mm mm 
20 80 260 
Table   D.6: Hard Chine vessels bottom stringers  
Measured  
length  Bottom stringers  
Spacing  Total section  
area per side  Moulding  Siding  
m mm mm2 mm mm 
20 355 24192  42 96 
Table   D.7: Hard Chine vessels Chines  
Vessels Chines  
Measured  length  Sectional  area Siding  Moulding  
m mm2 mm mm 
20 12168  78 156 
Table   D.8: Chines and Stringers (Single planked hulls)  
 Chines  Stringers  
Measured  Section  siding  moulding  Section area  siding  Moulding   
©TBS 2023 -All rights reserved  74 length  area per side  
m mm2 mm mm mm2 mm mm 
20 18375  105 175 36750  175 70 
Table   D.9: Hard Chine Vessels - Beam Shelf/ Sheer Clamp  
Measured length  Section area  
m mm2 
20 17200  
Table   D.10: Hard Chine Vessels - Hull Planking Thickness  
Measured  
length  Bottom  Topside  
Plywood  Double  
diagonal  Plywood  Double  diagonal  
m mm mm mm mm 
20 31 44 23 33 BCDC 12 (1829) DTZS  
 ©TBS 2023 -All rights reserved